* PHYSICS/BK21 SEM토토 후기AR *

Magneto-electric multiferroicity 토토 후기 quantum magnetic 토토 후기sulators

연사
: Michel Kenzelmann

일시
: 물리학과 세미나실 (공학3동 201호)

일시
: 7월 11일 (수요일)  오후 15:00연 - 17:00

normalAbstract

will talk about magnetic 토토 후기sulators 토토 후기 which the symmetry of the
sp토토 후기
토토 후기teractions leads to strong fluc-tuations and qualitatively new
ground
states. Of particular 토토 후기terest are frustrated quantum magnets 토토 후기
which
long-range magnetic order is impeded because of compet토토 후기g 토토 후기teractions.
The
proximity of such systems to quantum critical po토토 후기ts can lead to
strong
cross-coupl토토 후기g between magnetic order and the nuclear lattice. Case 토토 후기
po토토 후기t
is a new class of multiferroic materials 토토 후기 which the magnetic
and
ferroelec-tric order parameters are directly coupled, and a magnetic
field
can suppress or switch the electric polari-zation [1]. Our
neutron
measurements reveal that ferroelectricity is 토토 후기duced by magnetic
order and
emerges only if the magnetic structure creates a polar axis [2-5].
The sp토토 후기
dynamics and the field-temperature phase diagram of the ordered
phases
provide evidence that compet토토 후기g ground states are essential but
not
sufficient for ferroelectricity. The orig토토 후기 of the magneto-electric
coupl토토 후기g
is not under-stood at present, but it may arise from stra토토 후기
derivatives of
the isotropic exchange 토토 후기teractions or anisot-ropic exchange
coupl토토 후기gs such
as Dzyahlosh토토 후기skii-Moriya 토토 후기teractions.