We thank Prof. Takanishi for his help in our experiment. We also thank DIC Corporation for providing the compounds studied here. This work was supported by Grant-in-Aid for the JSPS Fellow (16J02711), JSPS KAKENHI Grant Number 17H01143, and the Program for Leading Graduate Schools &#34;Interactive Materials Cadet Program&#34;.

1. Preparation of Liquid-Crystal Cells and the Determination of the Cell Gap
<ol>
	<li>Preparation of liquid-crystal cells 
	<ol>
		<li>Cut glass substrates coated with indium/tin-oxide (ITO) on one side into the desired size (typical size: 10 x 10 x 1.1 mm, Figure 2A). To cut the substrates, scratch a line on their face with a glass cutter and break off excess glass manually.</li>
		<li>Wash the cut glass substrates using a detergent in an ultrasonic bath at 35 kHz for 30...

<ol>
	<li>Eerenstein, W., Mathur, N. D., Scott, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multiferroic+and+magnetoelectric+materials.">Multiferroic and magnetoelectric materials.</a> Nature. 442, 759-765 (2006).</li><li>Cheong, S. -. W., Mostovoy, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multiferroics:+A+magnetic+twist+for+ferroelectricity.">Multiferroics: A magnetic twist for ferroelectricity.</a> Nature Materials. 6, 13-20 (2007).</li><li>Tokura, Y., Seki, S., Nagaosa, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multiferroics+of+spin+origin.">Multiferroics of spin origin.</a> Reports on Progress in Physics. 77, 076501 (2014).</li><li>Fiebig, M., Lottermoser, T., Meier, D., Trassin, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+evolution+of+multiferroics.">The evolution of multiferroics.</a> Nature Reviews Materials. 1, 16046 (2016).</li><li>Kagawa, F., Horiuchi, S., Tokunaga, M., Fujioka, M., Tokura, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ferroelectricity+in+a+one-dimensional+organic+quantum+magnet.">Ferroelectricity in a one-dimensional organic quantum magnet.</a> Nature Physics. 6, 169-172 (2010).</li><li>Stroppa, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electric+Control+of+magnetization+and+interplay+between+orbital+ordering+and+ferroelectricity+in+a+multiferroic+metal-organic+framework.">Electric Control of magnetization and interplay between orbital ordering and ferroelectricity in a multiferroic metal-organic framework.</a> Angewandte Chemie International Edition. 50, 5847-5850 (2011).</li><li>Wang, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnetoelectric+coupling+in+the+paramagnetic+state+of+a+metal-organic+framework.">Magnetoelectric coupling in the paramagnetic state of a metal-organic framework.</a> Science Reports. 3, 2024 (2011).</li><li>G&#243;mez-Aguirre, L. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnetic+ordering-induced+multiferroic+behavior+in+[CH3NH3][Co(HCOO)3]+metal-organic+framework.">Magnetic ordering-induced multiferroic behavior in [CH3NH3][Co(HCOO)3] metal-organic framework.</a> Journal of the American Chemical Society. 138, 1122-1125 (2016).</li><li>Qin, W., Xu, B., Ren, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+organic+approach+for+nanostructured+multiferroics.">An organic approach for nanostructured multiferroics.</a> Nanoscale. 7, 9122-9132 (2015).</li><li>Scott, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Room-temperature+multiferroic+magnetoelectrics.">Room-temperature multiferroic magnetoelectrics.</a> NPG Asia Materials. 5, e72 (2013).</li><li>Suzuki, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+applied+electric+fields+on+the+positive+magneto-LC+effects+observed+in+the+ferroelectric+liquid+crystalline+phase+of+a+chiral+nitroxide+radical+compound.">Influence of applied electric fields on the positive magneto-LC effects observed in the ferroelectric liquid crystalline phase of a chiral nitroxide radical compound.</a> Soft Matter. 9, 4687-4692 (2013).</li><li>Domracheva, N. E., Ovchinnikov, I. V., Turanov, A. N., Konstantinov, V. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=EPR+detection+of+presumable+magnetoelectric+interactions+in+the+liquid-crystalline+state+of+an+iron+mesogen.">EPR detection of presumable magnetoelectric interactions in the liquid-crystalline state of an iron mesogen.</a> Journal of Magnetism and Magnetic Materials. 269, 385-392 (2004).</li><li>Toma&#353;ovi&#269;ov&#225;, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Capacitance+changes+in+ferronematic+liquid+crystals+induced+by+low+magnetic+fields.">Capacitance changes in ferronematic liquid crystals induced by low magnetic fields.</a> Phys. Rev. E. 87, 014501 (2013).</li><li>Lin, T. -. J., Chen, C. -. C., Lee, W., Cheng, S., Chen, Y. -. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrical+manipulation+of+magnetic+anisotropy+in+the+composite+of+liquid+crystals+and+ferromagnetic+nanorods.">Electrical manipulation of magnetic anisotropy in the composite of liquid crystals and ferromagnetic nanorods.</a> Applied Physics Letters. 93, 013108 (2008).</li><li>Mertelj, A., Osterman, N., Lisjak, D., &#268;opi&#269;, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magneto-optic+and+converse+magnetoelectric+effects+in+a+ferromagnetic+liquid+crystal.">Magneto-optic and converse magnetoelectric effects in a ferromagnetic liquid crystal.</a> Soft Matter. 10, 9065-9072 (2014).</li><li>Ueda, H., Akita, T., Uchida, Y., Kimura, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Room-temperature+magnetoelectric+effect+in+a+chiral+smectic+liquid+crystal.">Room-temperature magnetoelectric effect in a chiral smectic liquid crystal.</a> Applied Physics Letters. 111, 262901 (2017).</li><li>Clark, N. A., Lagerwall, S. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Submicrosecond+bistable+electro-optic+switching+in+liquid+crystals.">Submicrosecond bistable electro-optic switching in liquid crystals.</a> Applied Physics Letters. 36, 899-901 (1980).</li><li>Vantomme, G., Gelebart, A. H., Broer, D. J., Meijer, E. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+of+liquid+crystal+networks+for+macroscopic+oscillatory+motion+induced+by+light.">Preparation of liquid crystal networks for macroscopic oscillatory motion induced by light.</a> Journal of Visualized Experiments. (127), e56266 (2017).</li><li>Yang, K. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurements+of+empty+cell+gap+for+liquid-crystal+displays+using+interferometric+methods.">Measurements of empty cell gap for liquid-crystal displays using interferometric methods.</a> Journal of Applied Physics. 64 (9), 4780-4781 (1988).</li><li>Born, M., Wolf, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Principles of Optics. , (1987).</li><li>Dierking, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Textures of Liquid Crystals. , (2003).</li><li>Filipi&#269;, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dielectric+properties+near+the+smectic-C*+-smectic-A+phase+transition+of+some+ferroelectric+liquid-crystalline+systems+with+a+very+large+spontaneous+polarization.">Dielectric properties near the smectic-C* -smectic-A phase transition of some ferroelectric liquid-crystalline systems with a very large spontaneous polarization.</a> Physics Review A. 38, 5833-5839 (1988).</li><li>Carlsson, T., &#381;ek&#353;, B., Filipi&#269;, C., Levstik, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Theoretical+model+of+the+frequency+and+temperature+dependence+of+the+complex+dielectric+constant+of+ferroelectric+liquid+crystals+near+the+smectic-C*+-smectic-A+phase+transition.">Theoretical model of the frequency and temperature dependence of the complex dielectric constant of ferroelectric liquid crystals near the smectic-C* -smectic-A phase transition.</a> Physics Review A. 42, 877-889 (1990).</li><li>Michelson, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physical+realization+of+a+Lifshitz+point+in+liquid+crystals.">Physical realization of a Lifshitz point in liquid crystals.</a> Physical Review Letters. 39, 464 (1977).</li><li>Mu&#353;evi&#269;, I., &#381;ek&#353;, B., Blinc, R., Rasing, T., Wyder, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phase+diagram+of+a+ferroelectric+chiral+smectic+liquid+crystal+near+the+Lifshitz+point.">Phase diagram of a ferroelectric chiral smectic liquid crystal near the Lifshitz point.</a> Physical Review Letters. 48, 192 (1982).</li><li>Mu&#353;evi&#269;, I., &#381;ek&#353;, B., Blinc, R., Rasing, T., Wyder, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dielectric+study+of+the+modulated+smectic+C*-uniform+smectic+C+transition+in+a+magnetic+field.">Dielectric study of the modulated smectic C*-uniform smectic C transition in a magnetic field.</a> Physica Status Solidi(b). 119, 727-733 (1983).</li><li>Blinc, R., Mu&#353;evi&#269;, I., &#381;ek&#353;, B., Seppen, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ferroelectric+liquid+crystals+in+a+static+magnetic+field.">Ferroelectric liquid crystals in a static magnetic field.</a> Physica Scripta. 35, 38-43 (1991).</li><li>Blinov, L. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Electrooptical and Magnetooptical Properties of Liquid Crystals. , (1983).</li></ol>

The authors have nothing to disclose.

The experimental results showed that the methods described here successfully demonstrated the ME coupling in the liquid crystal. The observed ME and magneto-dielectric effects can be associated with the orientational transition of molecular orientation in a fixed smectic layer structure. However, the layer normal direction n0 in the layer structure can be also changed by applying a magnetic field through magnetic anisotropy. This is because the molecules prefer to have a parallel arra...

Research on the magnetoelectric (ME) effect, the induction of electric polarization (magnetization) by a magnetic (electric) field, has been focused towards the novel types of applications such as sensors and storage technologies. With recent studies on ME multiferroics1,2,3,4, the target systems in the field of ME study are extended to various types of solid-state materials, including inorganic, organic, and metal-organic frameworks, by utilizing spin-lattice couplings dexterously5,6,7,8,9. However, room-temperature operation, which must be accomplished for practical utilization of ME materials with their ME couplings, is still a challenging issue, and a very limited number of single-phase materials have been reported as room-temperature magnetoelectrics to date10.
Liquid crystals, which possess an orientational order, sometimes with a partial positional one, have also been examined with respect to ME materials in recent years11,12,13,14,15. One of the advantages of liquid crystals as ME materials is their operation temperature, as liquid-crystal phases are typically stabilized around room temperature. An example of ME liquid crystals reported so far is a composite between magnetic nano-platelets with perpendicular magnetic anisotropy and liquid crystals showing the nematic phase, known as the simplest liquid-crystal phase possessing only one-dimensional orientational order15. It shows the converse ME effect, the induction of magnetization by an electric field, through the electric-field manipulation of the coupled platelet and molecular orientations.
More recently, another unique strategy to establish the ME effect in liquid crystals was proposed16. The focus of this strategy is to create a chiral smectic C (SmC*) phase with one-dimensional positional order, resulting in a diffused layer structure called the smectic layer. One characteristic of the SmC* phase is that a molecular orientation vector n is coupled with a local electric dipole moment p. This correlation is provided by the combination of tilted orientation of the rod-like constituent molecules with respect to the smectic layer normal n0 and the chirality-induced mirror (and inversion) symmetry breaking in the molecules. From the viewpoint of symmetries, the former changes the symmetry from D&#8734;h (the so-called SmA phase, Figure 1A) into C2h (the so-called SmC phase, Figure 1B), and the latter breaks the mirror symmetry of C2h so that the symmetry is reduced into C2 (the SmC* phase, see each layer in Figure 1C). In each SmC* layer, the presence of finite polarization is allowed along the C2 axis, which is normal to both n0 and n. The strong coupling between n and p is essential for ferroelectricity in liquid crystals. In the SmC* phase, n aligns in the helicoidal manner through layer by layer (Figure 1C), and thus there is no macroscopic polarization. Ferroelectricity in such liquid crystals is achieved by using strong surface effects, which stabilize the homogeneously oriented state of n known as a surface-stabilized ferroelectric liquid-crystal (SSFLC) state (Figure 1D). It should be noted that ferroelectric polarization reversal always accompanies a switching of the bi-stable orientation states through the coupling between n and p17. As the inverse effect, a change in molecular orientation of the SmC* phase is expected to give rise to a change in electric polarization. Through magnetic anisotropy caused by spins on magnetic elements and/or aromatic rings in liquid-crystal molecules and the flexibility of n in a liquid-crystal state due to weaker molecular interactions than in a solid crystal state, n is also tunable by a magnetic field. Thus, the SmC* phase can be transformed into a magnetic-field-induced homogeneously oriented state similar to an SSFLC state. Therefore, the direct ME effect, the induction of electric polarization by a magnetic field, is achieved as the development of macroscopic electric polarization is induced by a homogeneous alignment of n coupled with p, in all the layers.
We introduce procedures to prepare liquid-crystal cells for the investigation of ME couplings and methodologies to detect the ME effect. A method for the preparation of liquid-crystal cells was reported in detail previously18. Here, we modified this method for dielectric and ME measurements. With the method detailed here, we detected magnetically-tuned electric polarization, that is, the direct ME effect, in a liquid crystal showing the SmC* phase at room temperature.

<table>
	<tbody>
		<tr>
			<td>Material</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Compound 1: Figure 4(A)</td>
			<td>DIC Co., Ltd.</td>
			<td>&#8211;N/A</td>
			<td>PYP-8O8</td>
		</tr>
		<tr>
			<td>Compound 2: Figure 4(B)</td>
			<td>DIC Co., Ltd.</td>
			<td>N/A</td>
			<td>PYP-10O10F</td>
		</tr>
		<tr>
			<td>ITO-coated glass substrates</td>
			<td>Sigma-Aldrich Inc.</td>
			<td>703192-10PK</td>
			<td></td>
		</tr>
		<tr>
			<td>Detergent</td>
			<td>Wako Pure Chemical Industries, Ltd.</td>
			<td>031-10401</td>
			<td></td>
		</tr>
		<tr>
			<td>Alignment layer planer</td>
			<td>JSR Co., Ltd.</td>
			<td>AL1254</td>
			<td></td>
		</tr>
		<tr>
			<td>Spacer</td>
			<td>Teijin Film Solutions Co., Ltd.</td>
			<td>Q51-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Glue</td>
			<td>Huntsman Inc.</td>
			<td>ARALDITE RT30</td>
			<td>For gluing two substrates</td>
		</tr>
		<tr>
			<td>Glue</td>
			<td>M&#38;I Materials ltd.</td>
			<td>Apiezon H Grease</td>
			<td>For gluing a cell and homemade insert</td>
		</tr>
		<tr>
			<td>Silver paste</td>
			<td>Fujikura Kasei Co., Ltd.</td>
			<td>D-753</td>
			<td></td>
		</tr>
		<tr>
			<td>Equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ultrasonic cleaner</td>
			<td>AS ONE Corp.</td>
			<td>AS52GTU</td>
			<td></td>
		</tr>
		<tr>
			<td>Spin coater</td>
			<td>Mikasa Co. Ltd.</td>
			<td>1H-D7</td>
			<td></td>
		</tr>
		<tr>
			<td>Polarized optical microscope</td>
			<td>Nikon Co., Ltd.</td>
			<td>ECLIPSE LV100N POL</td>
			<td></td>
		</tr>
		<tr>
			<td>Short-pass filter</td>
			<td>Thorlabs Inc.</td>
			<td>FB600-40</td>
			<td></td>
		</tr>
		<tr>
			<td>Optical spectrometer</td>
			<td>Ocean Optics Inc.</td>
			<td>USB2000+UV-VIS</td>
			<td></td>
		</tr>
		<tr>
			<td>Differential thermal analyzer</td>
			<td>Rigaku Co., Ltd.</td>
			<td>Thermo plus EVO2</td>
			<td></td>
		</tr>
		<tr>
			<td>Superconducting magnet</td>
			<td>Quantum Design Inc.</td>
			<td>PPMS</td>
			<td></td>
		</tr>
		<tr>
			<td>LCR meter</td>
			<td>Keysight Technologies Ltd.</td>
			<td>E4980A</td>
			<td></td>
		</tr>
		<tr>
			<td>Electrometer</td>
			<td>Keithley Instruments Inc.</td>
			<td>6517A</td>
			<td></td>
		</tr>
	</tbody>
</table>

measuring magnetically-tuned ferroelectric polarization in liquid crystals

Materials showing coupling phenomena between magnetism and (ferro)electricity, i.e., magnetoelectric effects, have attracted a great deal of attention due to their potential applications for future device technologies such as sensors and storage. However, conventional approaches, which usually utilize materials containing magnetic metal ions (or radicals), have a major problem: only a few materials have been found to show the coupling phenomena at room temperature. Recently, we proposed a new approach to achieve room-temperature magnetoelectrics. In contrast to conventional approaches, our alternative proposal focuses on a completely different material, a &#34;liquid crystal&#34;, free from magnetic metal ions. In such liquid crystals, a magnetic field can be utilized to control the orientational state of constituent molecules and the corresponding electric polarization through magnetic anisotropy of the molecules; it is an unprecedented mechanism of the magnetoelectric effect. In this context, this paper provides a protocol to measure ferroelectric properties induced by a magnetic field, that is, the direct magnetoelectric effect, in a liquid crystal. With the method detailed here, we successfully detected magnetically-tuned electric polarization in the chiral smectic C phase of a liquid crystal at room temperature. Taken together with the flexibility of constituent molecules, which directly affects the magnetoelectric responses, the introduced method will serve to allow liquid crystal cells to acquire more functions as room-temperature magnetoelectrics and associated optical materials.

The protocol is deemed a success only if the ME effect in liquid-crystal samples is observed. Here we measured the direct ME effect in a liquid-crystal sample prepared by the aforementioned procedures. For the measurements, an in-plane magnetic field was applied with the angle tilted by about 45&#176; from the rubbing direction (normal to smectic layers), because the largest magnetic-field-induced polarization was detected in this configuration16.
<p class="jov...

Watch this Scientific Journal Video about Measuring Magnetically-Tuned Ferroelectric Polarization in Liquid Crystals at JoVE.com

Measuring Magnetically-Tuned Ferroelectric Polarization in Liquid Crystals

In this report, we present a protocol to examine direct magnetoelectric effects, i.e., induction of ferroelectric polarization by applying magnetic fields, in liquid crystals. This protocol provides a unique approach, supported by the softness of liquid crystals, to achieve room-temperature magnetoelectrics.

Materials showing coupling phenomena between magnetism and (ferro)electricity, i.e., magnetoelectric effects, have attracted a great deal of attention due ...

This method can help answer key questions in the field of condensed matter physics and materials science on the room-temperature operation of the magnet electric effect. The main advantage of this technique is that it tests the magnet electric effect in liquid crystal with high fluidity. Begin with two glass substrates to create each liquid crystal cell.Start with clean substrates with ITO on one side, typically one square centimeter. Make a scratch on the edge of each substrate to help orient them in later steps. At a spin coater, drip polyimide solution onto the ITO-coded side of the substrates before spin coating.When done, bake the substrates at 200 degrees Celsius for one hour. Then take the substrates to an XZ stage that is under a velvet roller that can rotate. Orient a substrate ITO-side up and with its marked edge toward the roller, and fix it on the stage.Start the roller in the translation stage so the substrate moves back and forth under the roller five times. The substrate should experience soft, uniform pressure when in contact with the roller. Then stop the roller in translation stage to retrieve the substrate.When done, place the substrate in isopropyl alcohol for one minute. Then dry the substrates at 80 degrees Celsius for a few minutes. Now work with two rubbed substrates.In addition to the substrates, have flat resin film for a spacer. Place one substrate with its ITO and polyimide side up, and deposit glue at its edges. Next, orient the second substrate over the first with its coded side down.Orient the marked edges to be on opposite sides of the cell. Shift the two slightly before adhering them. Use the regions created by shifting the substrates to glue conducting wires with silver paste to the coded sides of the substrates.Bake the assembly at 150 degrees Celsius for one hour. Now use a setup similar to this to perform measurements of the cell gap. Place the cell so that it is perpendicular to a white light source and in front of an optical spectrometer for measuring the transmission spectrum.The measured transmittance as a function of wavelength allows determination of the cell gap, which is about 12 micrometers for this cell. To proceed, have the liquid crystal mixture in a cell ready. The liquid crystal mixture is comprised of these two pyrimidine compounds.75 milligrams of compound one, along with 25 milligrams of compound two. Put the prepared cell on a hot stage at 80 degrees Celsius. With a spatula, introduce the liquid crystal mixture to the cell, and rely on capillary action.Maintain the cell at 80 degrees Celsius for half an hour before cooling it to room temperature. The next step is to characterize the mixture. At a microscope, place a prepared sample in a hot stage between two crossed polarizers that are in line with the light source.Focus the microscope to observe the textures in the cell. Heat the sample at a rate of 5 degrees Celsius per minute from room temperature up to 80 degrees Celsius, and identify the liquid crystal phases from the polarization micrographs. Use the observations to determine the transition temperatures.The measurements require a superconducting magnet capable of a 9-Tesla field. Prepare an insert for the magnet that has a rod to house coaxial cables. At its head, there should be a connector terminal.At its end, there should be a sample space capable of holding a cell. Glue the cell on the sample space of the insert so the magnetic field is parallel to the substrate surfaces. Solder the cell's wires to the high and low terminals.Also place a thermometer on the widest length of the cell. When ready, introduce the insert into the superconducting magnet. With coaxial cables, connect the terminals of the insert to measurement instruments and gather data.Here is the electric polarization as a function of temperature, found by integrating the displacement current measured with an electrometer. In the smectic C-star phase, a finite polarization develops on applying a magnetic field at about 328 Kelvin. As the system undergoes a phase transition to the smectic A-star phase, the polarization disappears.These data are for the dielectric constant measured at 100 hertz using a quasi four-terminal method with an LCR meter. In the smectic C-star phase, it is suppressed as the magnetic field increases. This can be ascribed to the change in the molecular orientation state, coupled with the electric dipole moment.In the smectic A-star phase, the dielectric constant is independent of the magnetic field. Fixing the temperature allows for a clear demonstration of magnetoelectric activity. At 300 Kelvin, the sample is in the smectic C-star phase.Here the electric polarization varies with the changing magnetic field. The dielectric constant taken at 100 hertz shows similar behavior. Measurements performed at 335 Kelvin when the liquid crystal is in the smectic A-star phase do not depend on the magnetic field.So this method can provide insight into magnetically tunable electric polarization in liquid crystals. It can also be applied to other measurements, such as electrically controllable magnetism, and lighting optical effects in liquid crystals. After each development, this technique paves the way for researchers in the field of condensed matter physics and materials science, magnetoelectric coupling in liquid crystals.

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8.6K vues.  Osaka University. This method can help answer key questions in the field of condensed matter physics and materials science on the room-temperature operation of the magnet electric effect. The main advantage of this technique is that it tests the magnet electric effect in liquid crystal with high fluidity. Begin with two glass substrates to create each liquid crystal cell.Start with clean substrates with ITO on one side, typically one square centimeter. Make a scratch on the edge of each substrate to hel...