In:
Applied Physics Letters, AIP Publishing, Vol. 114, No. 21 ( 2019-05-27)
Abstract:
We generate terahertz (THz) transients by illuminating a few-nanometer-thick Ta/NiFe/Pt nanolayers with a train of linearly polarized 100-fs-wide laser pulses. The transients are ∼1-ps-wide free-space propagating bursts of electromagnetic radiations with amplitudes that are magnetically and optically tunable. Their spectral frequency content extends up to 5 THz, and the 3-dB cutoff is at 0.85 THz. The observed transient electromagnetic signals originate from the NiFe/Pt bilayer, and their amplitude dependence on the external magnetic field, applied in the sample plane, very closely follows the static magnetization versus magnetic field dependence of the NiFe film. For the same laser power, excitation with highly energetic, blue light generates THz transients with amplitudes approximately three times larger than the ones resulting from excitation by infrared light. In both cases, the transients exhibit the same spectral characteristics and are linearly polarized in the perpendicular direction to the sample magnetization. The polarization direction can be tuned by rotation of the magnetic field around the laser light propagation axis. The characteristics of our THz spintronic emitter signals confirm that THz transient generation is due to the inverse spin Hall effect in the Pt layer and demonstrate that ferromagnet/metal nanolayers excited by femtosecond laser pulses can serve as efficient sources of magnetically and optically tunable, polarized transient THz radiation.
Type of Medium:
Online Resource
ISSN:
0003-6951
,
1077-3118
Language:
English
Publisher:
AIP Publishing
Publication Date:
2019
detail.hit.zdb_id:
211245-0
detail.hit.zdb_id:
1469436-0
