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TT: Fachverband Tiefe Temperaturen

TT 22: Focus Session: Frustrated Magnetism and Local Order (joint session MA/TT)

TT 22.3: Hauptvortrag

Dienstag, 19. März 2024, 10:30–11:00, H 1058

Self-Induced Spin Glass Phase and Thermally Induced Order in dhcp Nd — •Anders Bergman — Uppsala University, Uppsala, Sweden

Among the wide variety of magnetic orders found in frustrated magnets, one of the most intriguing phases is manifested by the spin glass state where the magnetization exhibit glassy dynamics, including ageing and memory effects. The peculiar dynamics of spin glass materials has historically been associated with disorder where magnetic frustration can cause an energy landscape with several local minima combined with larger energy barriers, resulting in non-ergodic behavior and glassy dynamics.

Recent theoretical and experimental findings have however indicated the existence of glassy dynamics in a material with limited chemical disorder: elemental and crystalline Nd [1]. In this talk, we will present results indicating that: I) the low temperature state of dhcp Nd can be described as a self-induced spin glass and II) dhcp Nd undergoes a phase transition from the self-induced spin glass phase to an ordered spin-spiral phase with increasing temperature [2].

Using first-principles DFT calculations of magnetic exchange interactions combined with atomistic spin dynamics simulations we can show that the complex magnetism of dhcp Nd is driven by an intrinsic frustration of the exchange interactions between Nd atoms at the cubic and the hexagonal sites in the dhcp structure.

[1] U. Kamber, et. al, Science 6757 368 (2020)

[2] B. Verlhac, et. al, Nature Physics 905 18 (2022)

Keywords: spinn glass; frustrated magnets; atomistic spin dynamics; simulations; density functional theory