# Geometrically frustrated magnets with strong spin-orbit coupling

**Advisor:** Gael Bastien (MFF UK)

**Funding:** Fully funded.

**Contact:** Gael.bastien@mag.mff.cuni.cz

Magnetism is a fascinating research area, because it is a nice playground to study many body physics and statistical mechanics and also thanks to the possible applications in electronics or energy management. Frustrated magnets are magnetic materials, where all the magnetic interactions cannot be simultaneously satisfied and thus compete with each other. In these materials a large variety of magnetically ordered states and disorder states such as the quantum spin liquid state can be found. The quantum spin liquid state is an intriguing state of matter with quantum entanglement between neighboring magnetic moments, but without any long-range magnetic order. The magnetic frustration was investigated in details in past decades in particular with 3d transition metals as magnetic ions. Recently this field was enlarged with the use of heavier magnetic ions, where the strong spin-orbit coupling reinforces magnetic frustration via additional constraints on magnetic moment directions [1] [2].

In the present thesis, the magnetic properties of few recently discovered rare earth based triangular lattice antiferromagnets will be investigated. The precise choice of compounds will presumably be among the families: REM3X3 (RE=rare earth, M=Zn, Cd, X=P, As) [3][4], REMAl11O19 (RE=rare earth, M=Mg, Zn) [5] and/or RE(BaBO3)3 (RE=rare earth) [6] and will be evaluated with the student considering interests, opportunities and risks. The work includes crystal growth, structural analysis and measurements of physical properties such as magnetization and specific heat down to temperatures of few tenth of millikelvin. In addition, the student may perform measurements on large scale user facilities such as neutron scattering or muon spectroscopy.

Figure adapted from references [1] and [4].

# Literature:

[1] Y. Li, P. Gegenwart, and A. A.
Tsirlin, Journal of Physics: Condensed Matter, 32, 224004 (2020) https://arxiv.org/abs/1911.11157

[2]
G. Bastien, B. Rubrecht, E. Haeussler, P. Schlender, Z. Zangeneh, S. Avdoshenko,
R. Sarkar, A. Alfonsov, S. Luther, Y. A. Onykiienko, H. C. Walker, H. Kühne, V.
Grinenko, Z. Guguchia, V. Kataev, H. -H. Klauss, L. Hozoi, J. van den Brink, D.
S. Inosov, B. Büchner, A. U. B. Wolter, T. Doert, SciPost Phys. 9, 041 (2020)
https://scipost.org/10.21468/SciPostPhys.9.3.041

[3]
S. S. Stoyko and A. Mar. Inorg. Chem., 50, 11152 (2011) https://doi.org/10.1021/ic201708x

[4]
N. Kabeya, T. Sakamoto, K. Hara, Y. Hara, S. Nakamura, K. Katoh and A. Ochiai,
Journal of the Physical Society of Japan 89, 074707 (2020) https://doi.org/10.7566/JPSJ.89.074707

[5]
M. Ashtar, M. A. Marwat, Y. X. Gao, Z. T. Zhang, L. Pi, S. L. Yuan, and Z. M.
Tian. J. Mater. Chem. C, 7,10073 (2019). http://dx.doi.org/10.1039/C9TC02643F

[6]
K. Y. Zeng, L. Ma, Y. X. Gao, Z. M. Tian, L. S. Ling, and L. Pi. Phys. Rev. B 102, 045149 (2020) https://arxiv.org/abs/1912.03814.