Abstract
Understanding the interaction between intense terahertz (THz) electromagnetic fields and spin systems has been gaining importance in modern spintronics research as a unique pathway to realize ultrafast macroscopic magnetization control. In this work, we used intense THz pulses with pulse energies in the order of 10 mJ/pulse generated from the terahertz free electron laser (THz-FEL) to irradiate the ferromagnetic domains of ErFeO3 single crystal. It was found that the domain shape can be locally reconfigured by irradiating the THz − FEL pulses near the domain boundary. Observed domain reconfiguration mechanism can be phenomenologically understood by the combination of depinning effect and the entropic force due to local thermal gradient exerted by terahertz irradiation. Our finding opens up a new possibility of realizing thermal-spin effects at THz frequency ranges by using THz-FEL pulses.
Highlights
Understanding the interaction between intense terahertz (THz) electromagnetic fields and spin systems has been gaining importance in modern spintronics research as a unique pathway to realize ultrafast macroscopic magnetization control
One can expect that the irradiation of such ultrastrong terahertz free electron laser (THz-free electron lasers (FEL)) pulses on spin systems could potentially lead to macroscopic change of the magnetization by strongly perturbing critical order parameters such as anisotropy, exchange interactions, and domain wall mobility[27,28,29]
We found that magnetic domain shapes can be permanently reconfigured upon irradiation by THz-FEL, without causing permanent damage in the sample
Summary
Understanding the interaction between intense terahertz (THz) electromagnetic fields and spin systems has been gaining importance in modern spintronics research as a unique pathway to realize ultrafast macroscopic magnetization control. We used intense THz pulses with pulse energies in the order of 10 mJ/pulse generated from the terahertz free electron laser (THz-FEL) to irradiate the ferromagnetic domains of ErFeO3 single crystal. The extremely high pulse energy contained in THz-FEL is known to enable even destructive phenomena such as desorption of molecules[23,24] and amorphous-crystalline phase transition[5,25,26], to count a few In this context, one can expect that the irradiation of such ultrastrong THz-FEL pulses on spin systems could potentially lead to macroscopic change of the magnetization by strongly perturbing critical order parameters such as anisotropy, exchange interactions, and domain wall mobility[27,28,29]. Our result demonstrates the potential of THz−FEL as a novel light source for the investigation of thermally induced spin dynamics in the THz region, and paves way for the THz spintronic devices in future
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