Ultrafast spontaneous spin switching in an antiferromagnet

Abstract

Owing to their high magnon frequencies, antiferromagnets are key materials for future high-speed spintronics. Picosecond switching of antiferromagnetic order 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 modes, 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.

arXiv comment11 page main manuscript and 4 page Supplementary Material, 5 main figures and 5 Supplementary Figures

References in corpus (12)

• Antiferromagnetic spintronics
• Spin Caloritronics
• Petahertz Spintronics
• Raman spectroscopy of rare-earth orthoferrites RFeO3 (R = La, Sm, Eu, Gd, Tb, Dy)
• Spectroscopy of spontaneous spin noise as a probe of spin dynamics and magnetic resonance
• Electric field correlation measurements on the electromagnetic vacuum state
• Subcycle Quantum Electrodynamics
• Demonstration of nanosecond operation in stochastic magnetic tunnel junctions
• Probabilistic computing with p-bits
• Optical measurements of spin noise as a high resolution spectroscopic tool
• Two-color spin noise spectroscopy: Using spin fluctuation correlations to reveal homogeneous linewidths within quantum dot ensembles
• Magnetic susceptibility and magnetization fluctuation measurements of mixed Gadolinium-Yttrium Iron Garnets

Cited by in corpus (7)

• Multimode Phonon-Polaritons in Lead-Halide Perovskites in the Ultrastrong Coupling Regime
• Frequency Dependence of Phonon-Induced Current Noise in ArmchairCarbon Nanotube
• Subharmonic lock-in detection and its optimisation for femtosecond noise correlation spectroscopy
• Quantifying the amplitudes of ultrafast magnetization fluctuations in Sm${}_{0.7}$Er${}_{0.3}$FeO${}_3$ using femtosecond noise correlation spectroscopy
• Fluctuations in Spin Dynamics Excited by Pulsed Light
• Switching of an antiferromagnet controlled by spin canting in a laser-induced hidden phase
• Field-tuning of ultrafast magnetization fluctuations in Sm${}_{0.7}$Er${}_{0.3}$FeO${}_3$