Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 4: Spin structures and magnetic phase transitions
MA 4.6: Vortrag
Montag, 12. März 2018, 10:45–11:00, EB 202
Metamagnetic anomalies near dynamic phase transitions — •Patricia Riego1,2, Paolo Vavassori1,3, and Andreas Berger1 — 1CIC nanoGUNE, San Sebastian, Spain — 2University of the Basque Country, Bilbao, Spain — 3Ikerbasque, Bilbao, Spain
Ferromagnets that are subjected to an oscillating magnetic field H(t) can undergo a second order dynamic phase transition (DPT) at a critical period Pc, when the period P of H(t) becomes comparable to the intrinsic relaxation time of the system, which then gives rise to a non-vanishing period-averaged magnetization for P<Pc [1]. Decades of research have shown that the DPT belongs to the same universality class as the corresponding thermodynamic phase transition (TPT) that spin systems undergo as a function of temperature, and that both phase transitions exhibit equivalent properties close to the critical point [2,3]. In our detailed experimental and theoretical study, however, we find that the equivalency between DPTs and TPTs breaks down in the regime of slow critical dynamics [4]. Instead, we observe a dynamically disordered phase that exhibits metamagnetic anomalies that are absent in TPTs for equivalent spin systems. Furthermore, we show that the scaling regime of the DPT is significantly reduced, which has severely impacted all existing experiments on the DPT to date.
[1] T. Tomé and M. J. de Oliveira, Phys. Rev. A 41, 4251 (1990). [2] G. Korniss, C. J. White, P. A. Rikvold, and M. A. Novotny, Phys. Rev. E 63, 016120 (2000). [3] A. Berger, O. Idigoras, and P. Vavassori, Phys. Rev. Lett. 111, 190602 (2013). [4] P. Riego, P. Vavassori, and A. Berger, Phys. Rev. Lett. 118, 117202 (2017).