[seminar] 07. 10. 2022. Fabrice Bert, Université Paris-Saclay

[Damjan Pelc]

Drage kolegice i kolege,
zadovoljstvo nam je pozvati vas na sljedeći seminar Fizičkog odsjeka:

Dear colleagues,
it is our pleasure to invite you to the following seminar of the Physics
Department:

Petak/Friday *7.10.2022. 10 h, F-201*

Structure and magnetism of Y-kapellasite with a distorted kagome lattice

Fabrice Bert,
Laboratoire de Physique des Solides, Université Paris-Saclay, France

Quantum spin liquids are novel magnetic states of matter characterized by
the absence of phase transition down to T=0 K, macroscopic entanglement and
emergent fractionalized excitations. The quest for materials realizing such
states recently yielded a new family of interesting kagome compounds
resulting from the substitution of Zn2+ by Y3+ in the archetypal
herbertsmithite ZnCu3(OH)6Cl2 . While charge doping, the initial motivation
for the substitution, is not successful, the new materials YCu3(OH)6OxCl3−x
(x= 0, 1/3), sometimes coined Y-kapellasite, do not show measurable
dilution of the magnetic lattice and provide us with new variations of the
kagome structure. The x=0 compound features a perfect kagome geometry and a
strong Dzyaloshinskii-Moriya anisotropy which drives a q=0 long range order
below 15 K [1]. Here, we present a detailed study using NMR, μSR and
neutron scattering techniques of the x=1/3 counterpart which materializes
an original anisotropic kagome lattice with 3 different nearest neighbor
interactions. NMR and neutron diffraction studies demonstrate the
occurrence of a definite structural transition at 33 K and a weaker one at
13 K. These subtle transitions which preserve the global symmetry mainly
involve changes in the hydrogen positions. Further, our results provide
clear evidence for a magnetic transition at ∼ 2.1 K from complementary
experimental methods in contrast to the dynamical ground state reported for
powder samples [2] but in line with the theoretical prediction of a
(1/3,1/3) long range order [3].

[1] A Zorko et al , Physical Review B, 99 (21), 214441 (2019)
[2] Quentin. et al , Phys. Rev. Materials, 3 (7), 074401 (2019)
[3] Hering et al , npj Comput Mater 8, 10 (2022).

Lijep pozdrav / Best regards
Sanjin Benić i Damjan Pelc
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