[Landau ITP Seminars] семинары М.Е.Житомирского

[Pavel Ioselevich]

Дорогие коллеги,

Международная лаборатория физики конденсированного состояния НИУ ВШЭ приглашает на доклады М. Житомирского.


В четверг 8 ноября в 11:00
ИФП им. П.Л.Капицы РАН, ул. Косыгина, д.2

М.Е.Житомирский (CEA, Гренобль)

Multi-k states in frustrated spinel and kagome antiferromagnets

Competing exchange interactions may produce various non-collinear spin structures. Still majority of such magnetic states are coplanar with non coplanar states presented by only a few known examples. We investigate the multi-k magnetic structures with commensurate propagation wave vectors that can appear in spinel and kagome materials. 
For the isotropic Heisenberg Hamiltonian we find that the triple-k configurations are the most stable states in zero field for both systems. With increasing magnetic field they universally transform into the double-k magnetic structures. We also study the effect of magnetic anisotropies on the equilibrium spin configurations and in particular demonstrate that the splitting of the transition in GeNi2O4 is naturally explained by the local easy-plane anisotropy.


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Во вторник 13 ноября в 11:00
Ст.Басманная д.21/4, стр.5, ауд. Б-813 (8 этаж)

М.Е.Житомирский (CEA, Гренобль)

Interacting quasiparticles in quantum magnets: spin-wave decay and magnon pairing

Quantum solids, liquids, and magnets typically exhibit collective excitations - phonons, magnons and so on.
These involve motion of many constituent particles, yet act like individual weakly interacting entities —
quasiparticles. Recently, two new phenomena have been predicted in the field of Quantum Magnetism, where 
residual quasiparticle interactions play a paramount role. The first example is spontaneous magnon decay, 
which occurs at zero temperature and is inherent to noncollinear magnetic structures and spin liquids. 
The second effect corresponds to formation of bound magnon pairs in spin systems with competing ferro- and 
antiferromagnetic interactions. Their subsequent condensation in an applied magnetic field produces novel 
spin nematic states. I shall present an overview of main theoretical approaches to both phenomena and also 
discuss possible experimental observations of such effects.

При необходимости заказа пропуска в НИУ ВШЭ обращайтесь к Ирине Аванесовой, iavanesova at hse.ru <https://e.mail.ru/compose/?mailto=mailto%3aiavanesova@hse.ru>
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