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SUMMARY:Multiferroics: from magnetoelectric memories to photonic devices
DTSTART:20170309T101500
DTEND:20170309T111500
DTSTAMP:20261001T181434Z
UID:015d0af33001cda173ec4074913025e46b8a3db5c533415bc7fa463d
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Istvan Kezsmarki\, Budapest University of Technology an
 d Economics\nIn conventional media light propagation is reciprocal\, that 
 is counter-propagating beams experience the same refractive index. However
 \, reciprocity can be violated in magnetoelectric materials\, where the re
 fractive index depends not only on the polarization of light but also on t
 he ±k direction of the propagation [1]. Such unidirectional transmission 
 is the consequence of the dynamic magnetoelectric effect emerging in mater
 ials with simultaneously broken time reversal and spatial inversion symmet
 ries. This phenomenon\, which has been exclusively observed in non-centros
 ymmetric (polar or chiral) materials with finite magnetization [2-5]\, may
  allow the development of optical diodes transmitting unpolarized light in
  one\, but not in the opposite\, direction [5].\nHere\, we demonstrate tha
 t LiCoPO4 with a fully compensated antiferromagnetic ground state\, i.e. w
 ith zero net magnetization\, can also exhibit unidirectional transmission 
 [6]. Following an appropriate magnetoelectric poling in crossed electric a
 nd magnetic fields\, we succeeded to realize the unidirectional transmissi
 on as a remnant effect in this compound. The unidirectional transmission l
 ikely originates from a ferrotoroidic order which can be viewed as the cro
 ss-product of antiferroelectricity and antiferromagnetism coexisting in Li
 CoPO4. The sign of the magnetoelectric effect can be set by the poling ele
 ctric and magnetic fields via the establishment of mono-domain ferrotoroid
 ic states\, and can be read via the optical-diode effect.  \n[1] D. Szall
 er\, S. Bordacs and I. Kezsmarki\, Phys. Rev. B 87\, 014421 (2014).\n[2] I
 . Kezsmarki et al.\, Phys. Rev. Lett. 106\, 057403 (2011).\n[3] S. Bordacs
  et al.\, Nat. Phys. 8\, 734 (2012).\n[4] I. Kezsmarki et al.\, Nat. Commu
 n. 5\, 3203 (2014).\n[5] I. Kezsmarki et al.\, Phys. Rev. Lett. 115\, 1272
 03 (2015).\n[6] V. Kocsis et al.\, to be published.
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STATUS:CONFIRMED
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