SKM 2023 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 46: Ultrafast Magnetization Effects II

MA 46.6: Vortrag

Freitag, 31. März 2023, 10:45–11:00, HSZ 02

Non-collinear spin reorientation in FeRh from first principles: Ultrafast laser quenching vs. coherent rotation of Fe moments — •Mike Jos Bruckhoff, Markus Ernst Gruner, and Rossitza Pentcheva — Faculty of Physics and Center for Nanointegration (CENIDE), University of Duisburg - Essen

The binary alloy FeRh exhibits a metamagnetic first-order phase transition from antiferromagnetic (AFM) to ferromagnetic (FM) order, which can be driven by an external magnetic field or laser excitation. Here, we present a comprehensive non-collinear density functional theory study, where we investigate the multidimensional energy landscape E(M,V), by constraining the total spin moment in order to compare different kinds of spin reorientation pathways. The absence of significant energy barriers suggests that the coherent in-plane rotation of the Fe moments is a likely scenario for the magnetic phase transition in an external magnetic field. In contrast to this, FeRh exhibits an laser-induced ultrafast demagnetization, which is initiated by optical inter-site spin transfer (OISTR) and a net Rh-to-Fe charge transfer at early times after excitation. We study extensively the response of FeRh to laser pulses with different laser parameters in both magnetic phases, simulated by means of real-time time-dependent DFT (RT-TDDFT). We find that the magnitude of the response strongly depends on the incident laser pulse, as well as the magnetic state of FeRh. We conclude that laser excitations and applied magnetic fields initiate distinct transition pathways, which may be exploited to control the phase transition by the external stimuli.