Condensed-Matter Physics & Materials Science Seminar
"Engineering magnetism with light with the novel photovoltaic perovskite CH3NH3PbI3"
Presented by László Forró, Ecole Polytechnique Fédérale de Lausanne, Switzerland
Thursday, October 24, 2019, 2:30 pm — ISB Bldg. 734 Conf. Rm. 201 (upstairs)
The demand for ever-increasing density of information storage and speed of manipulation boosts an intense search for new magnetic materials and novel ways of controlling the magnetic bit. Here, we report the synthesis of a ferromagnetic photovoltaic CH3NH3(Mn:Pb)I3 material in which the photo-excited electrons rapidly melt the local magnetic order through the Ruderman–Kittel–Kasuya–Yosida interactions without heating up the spin system (1). Similar effect was observed in La1-xSrxMnO3/CH3NH3PbI3 heterostructure in which Tc can be tuned by x (2). The observed optical melting of magnetism could be of practical importance, for example, in a magnetic thin film of a hard drive, where a small magnetic writing field could change the magnetic bit. Our method needs only a low-power visible light source, providing isothermal switching, and a small magnetic guide-field to overcompensate the stray field of neighboring bits. Acknowledgment: The work has been performed in collaboration with B. Náfrádi, E. Horváth, A, Arakcheeva, P. Szirmai, M. Spina, H. Lee, O.V. Yazyev, D. Chernyshov, and many others. The research was partially supported by the ERC Advanced Grant (PICOPROP#670918). Reference : 1. Nafradi et al, Nature Communications, 7, 13406, (2016) 2. Nafradi et al, submitted to PNAS
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