Ultrafast magnetic dynamics in insulating YBa2Cu3O6.1 revealed by time resolved two-magnon Raman scattering

Jhih-An Yang,Dmitry Reznik,Nicholas Pellatz,Thomas Wolf,Rahul Nandkishore

doi:10.1038/s41467-020-16275-9

Jhih-An Yang, Dmitry Reznik + Show 3 more

Open Access

https://doi.org/10.1038/s41467-020-16275-9

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Abstract

Measurement and control of magnetic order and correlations in real time is a rapidly developing scientific area relevant for magnetic memory and spintronics. In these experiments an ultrashort laser pulse (pump) is first absorbed by excitations carrying electric dipole moment. These then give their energy to the magnetic subsystem monitored by a time-resolved probe. A lot of progress has been made in investigations of ferromagnets but antiferromagnets are more challenging. Here, we introduce time-resolved two-magnon Raman scattering as a real time probe of magnetic correlations especially well-suited for antiferromagnets. Its application to the antiferromagnetic charge transfer insulator YBa2Cu3O6.1 revealed rapid demagnetization within 90 fs of photoexcitation. The relaxation back to thermal equilibrium is characterized by much slower timescales. We interpret these results in terms of slow relaxation of the charge sector and rapid equilibration of the magnetic sector to a prethermal state characterized by parameters that change slowly as the charge sector relaxes.

Highlights

Measurement and control of magnetic order and correlations in real time is a rapidly developing scientific area relevant for magnetic memory and spintronics
We developed it while investigating YBa2Cu3O6.1 (YBCO), which is of broad interest as an AF charge transfer (CT) insulator whose hole doping leads to high-temperature superconductivity (Fig. 1a)
Its fundamental 790 nm (≈1.5 eV) laser pulses, whose photon energy happens to be very close to the YBCO CT gap, were used as the pump

Summary

Introduction

Measurement and control of magnetic order and correlations in real time is a rapidly developing scientific area relevant for magnetic memory and spintronics. Two-magnon (2M) Raman scattering from ultrafast laser pulses used as a probe fills this gap. 2M Raman scattering is sensitive to short-range AF order and is a powerful tool for the study of magnetic excitations and correlations.

Results

Conclusion