Discovery of ultrafast spontaneous spin switching in an antiferromagnet by femtosecond noise correlation spectroscopy

被引：10

作者：

Weiss, M. A. ^{[1
]}

Herbst, A. ^{[1
]}

Schlegel, J. ^{[1
]}

Dannegger, T. ^{[1
]}

Evers, M. ^{[1
]}

Donges, A. ^{[1
]}

Nakajima, M. ^{[2
]}

Leitenstorfer, A. ^{[1
]}

Goennenwein, S. T. B. ^{[1
]}

Nowak, U. ^{[1
]}

Kurihara, T. ^{[1
,3
]}

机构：

[1] Univ Konstanz, Dept Phys, D-78457 Constance, Germany

[2] Osaka Univ, Inst Laser Engn, Osaka 5650871, Japan

[3] Univ Tokyo, Inst Solid State Phys, Kashiwa 2778581, Japan

来源：

NATURE COMMUNICATIONS | 2023年 / 14卷 / 01期

基金：

日本学术振兴会;

关键词：

SUSCEPTIBILITY; SPECTRUM;

D O I：

10.1038/s41467-023-43318-8

中图分类号：

O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];

学科分类号：

07 ; 0710 ; 09 ;

摘要：

Owing to their high magnon frequencies, antiferromagnets are key materials for future high-speed spintronics. Picosecond switching of antiferromagnetic spin systems has been viewed a milestone for decades and pursued only by using ultrafast external perturbations. Here, we show that picosecond spin switching occurs spontaneously due to thermal fluctuations in the antiferromagnetic orthoferrite Sm0.7Er0.3FeO3. By analysing the correlation between the pulse-to-pulse polarisation fluctuations of two femtosecond optical probes, we extract the autocorrelation of incoherent magnon fluctuations. We observe a strong enhancement of the magnon fluctuation amplitude and the coherence time around the critical temperature of the spin reorientation transition. The spectrum shows two distinct features, one corresponding to the quasi-ferromagnetic mode and another one which has not been previously reported in pump-probe experiments. Comparison to a stochastic spin dynamics simulation reveals this new mode as smoking gun of ultrafast spontaneous spin switching within the double-well anisotropy potential. Antiferromagnets exhibit high frequency magnons, in the THz regime, a point potentially useful for applications, however, it has meant that detecting spin-fluctuations in antiferromagnets is typically too fast for current experimental approaches. Here Weiss et al use femtosecond noise correlation spectroscopy to observe magnon fluctuations in Sm0.7Er0.3FeO3.

引用

页数：9

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