Asymmetry in Standard model: Experimentally obtained:

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1 Asymmetry in Standard model: Experimentally obtained:

2 Výzkum a praktické využití magnetických feroelektrik Stanislav Kamba Fyzikální ústav AVČR, Na Slovance 2, 182 21 Praha 8 kamba@fzu.cz Multiferoika jsou materiály, ve kterých koexistují dvě a více feroických vlastností. Ferroelectric Ferrotoroidic Ferroelastic Ferromagnetic

3 Bibes & Barthélémy, Nature Materials, 7, 425 (2008) Chen et al. APL 89, 202508 (2006) Sketch of MERAM element

4 M. Gajek et al. Nature Materials, 6, 296 (2007) La 0.1 Bi 0.9 MnO 3 magnetoferroelectrics, 2 nm thin film Tunnel junctions with multiferroic barriers M  || M  M  || M 

5 Béa et al. JPCM 20, 434221(2008) Fiebig, J. Phys. D: Appl. Phys. 38, R123 (2005) Classification of insulating oxides

6 Multiferroics with spiral magnetic structure TbMnO 3, T N =40 K, T C =27 K Kimura et al. Nature 426, 55 (2003) T. Kimura Annu. Rev. Mater. Res. 37, 387 (2007 )

7 Different types of multiferroics •Type-II: Magnetically driven multiferroics, T C < T N a)Multiferroics with spiral magnetic structure The inverse Dzyaloshinskii-Moriya mechanism  - constant proportional to the spin orbit coupling and superexchange interaction e ij – unit vector connecting the neighboring i and j sites b) Multiferroics with collinear magnetic structure Symmetric (S i.S j )- type interaction, termed (super)exchange striction H. Kimura et al. J. Phys. Soc. Jpn. 75, 113701 (2006 ) T. Kimura Annu. Rev. Mater. Res. 37, 387 (2007 )

8 Strain induced ferroelectricity and ferromagnetism in tensile strained EuTiO 3 /DyScO 3 Lee et al. Nature 466, 954 (2010)FZÚ AVČR; kamba@fzu.cz

9 Strain-induced ferroelectric phase transition in EuTiO 3 /DyScO 3 +1% tensile strain Lee et al. Nature 466, 954 (2010) P S  30  C/cm 2 Nature 476, 114 (2011)

10 Strain induced ferromagnetism in tensile strained EuTiO 3 /DyScO 3 Lee et al. Nature 466, 954 (2010)

11 Magnetic dependence of TO1 phonon frequencyEuTiO 3 / LSAT Kamba et al. PRB 85, 094435 (2012)

12 Comples THz spectra of YMnO 3 single crystal Kadlec et al. PRB 84, 174120 (2011)

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14 Predictions for the EDM magnitude of electrone

15 • d = a s; switching the electric dipole moment switches the spin moment •Material property requirements: –Ferroelectric, switchable at few K, large polarization –Magnetic, but not ordered at a few K –Macroscopic sample (around 1 cm) –A low temperature multiferroic! Electron with an electric dipole moment K.Z. Rushchanskii et al., Nature Materials, 9, 649(2010) + - + - switch d with E or switch s with H

16 EuTiO 3 T N =7 K paraelectric a=3.9 Å BaTiO 3 ferroelectric a=4.0 Å (Eu,Ba)TiO 3

17 Dielectric and magnetic properties of Eu 0.5 Ba 0.5 TiO 3 Cubic Pm3mOrthorhombic Amm2 T C =215 KT N =1.9 KT Rushchankii et al., Nature Materials, 9, 649 (2010) V. Goian et al. JPCM 23, 025904 (2011) S. Kamba, Čs. čas. fyz. 60, 329 (2010)

18 „THz mezera” 10 0 10 3 10 6 10 9 10 12 10 15 10 18 10 21 10 24 kilo mega giga tera peta exa zetta yotta radiové vlny mikro- vlny nízké frekvence viditelnértg. záření gamma ELEKTRONIKA OPTIKA frekvence [Hz] „tradiční“ zdroje – příliš slabé:  Při frekvencích > 10 GHz klesá účinnost obvodů: elektrony nestačí sledovat rychlé změny elmg. pole Při frekvencích < 10 THz optické zdroje září málo vlnová délka 1000 km 1 km 1 m 1 mm 1 μ m 1 nm 1 pm 1 fm Infrač. UV Elekromagnetické spektrum FZÚ AVČR; kamba@fzu.cz

19 I.3. Dielectric spectrum Dielectric spectrum – a sum of the dielectric dispersion regions A set of the frequency - temperature dependences should be studied FZÚ AVČR; kamba@fzu.cz

20 THz laboratoř FZÚ AVČR; kamba@fzu.cz

21 Magnetický kryostat v THz laboratoři FZÚ AVČR; kamba@fzu.cz

22 Infračervená laboratoř FZÚ AVČR; kamba@fzu.cz