The nature of the ultrafast magnetic phase transition in nickel revealed by correlating EUV-MOKE and ARPES spectroscopies
1 Department of Physics and JILA, University of Colorado and NIST, Boulder, Colorado 80309, United States
2 State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200438, People’s Republic of China
3 National Institute of Standards and Technology (NIST), 325 Broadway, Boulder, Colorado 80305, United States
4 Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
* Corresponding author: ZhenshengTao@fudan.edu.cn
Published online: 16 April 2019
By correlating time- and angle-resolved photoemission (Tr-ARPES) and time-resolved transverse- magneto-optical Kerr effect (Tr-TMOKE) measurements, both at extreme ultraviolet (EUV) wavelengths, we uncover the nature of the ultrafast photoinduced magnetic phase transition in Ni. This allows us to explain the ultrafast magnetic response of Ni at all laser fluences - from a small reduction of the magnetization at low laser fluences, to complete quenching at high laser fluences. We provide an alternative explanation to the fluence-dependent recovery timescales commonly observed in ultrafast magneto-optical spectroscopies on ferromagnets: it is due to the bulk-averaging effect and different depths of sample exhibit distinct dynamics, depending on whether a magnetic phase transition is induced. We also show evidence of two competing channels with two distinct timescales in the recovery process, that suggest the presence of coexisting phases in the material.
© The Authors, published by EDP Sciences, 2019
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