Ultrafast spin-to-charge conversions of antiferromagnetic (111)-oriented L12\mathrm{L1_2}-Mn3Ir\mathrm{Mn_3Ir}

Antiferromagnetic $\mathrm{L1_2}$-$\mathrm{Mn_3Ir}$ combines outstanding spin-transport properties with magnons in the terahertz (THz) frequency range. However, the THz radiation emitted by ultrafast spin-to-charge conversion via the inverse spin Hall effect remains unexplored. In this study, we measured the THz emission and transmission of a permalloy/(111)-oriented $\mathrm{L1_2}$-$\mathrm{Mn_3Ir}$ multilayer by THz time-domain spectroscopy. The spin Hall angle was determined to be approximately constant at 0.024 within a frequency range of 0.3-2.2 THz, in comparison with the THz spectroscopy of a permalloy/Pt multilayer. Our results not only demonstrate the potential of $\mathrm{L1_2}$-$\mathrm{Mn_3Ir}$ as a spintronic THz emitter but also provide insights into the THz spin transport properties of $\mathrm{L1_2}$-$\mathrm{Mn_3Ir}$.Comment: 11 pages, 5 figure

Three-dimensional visualization of magnetic domain structure with strong uniaxial anisotropy via scanning hard X-ray microtomography

An X-ray tomographic technique was developed to investigate the internal magnetic domain structure in a micrometer-sized ferromagnetic sample. The technique is based on a scanning hard X-ray nanoprobe using X-ray magnetic circular dichroism (XMCD). From transmission XMCD images at the Gd L3 edge as a function of the sample rotation angle, the three-dimensional (3D) distribution of a single component of the magnetic vector in a GdFeCo microdisc was reconstructed with a spatial resolution of 360 nm, using a modified algebraic reconstruction algorithm. The method is applicable to practical magnetic materials and can be extended to 3D visualization of the magnetic domain formation process under external magnetic fields

Correlation of the Dzyaloshinskii–Moriya interaction with Heisenberg exchange and orbital asphericity

原子磁石どうしが捻れて並ぶ現象のミクロな起源を解明 --新原理の情報記録技術をめざして--. 京都大学プレスリリース. 2018-05-01.Chiral spin textures of a ferromagnetic layer in contact to a heavy non-magnetic metal, such as Néel-type domain walls and skyrmions, have been studied intensively because of their potential for future nanomagnetic devices. The Dyzaloshinskii–Moriya interaction (DMI) is an essential phenomenon for the formation of such chiral spin textures. In spite of recent theoretical progress aiming at understanding the microscopic origin of the DMI, an experimental investigation unravelling the physics at stake is still required. Here we experimentally demonstrate the close correlation of the DMI with the anisotropy of the orbital magnetic moment and with the magnetic dipole moment of the ferromagnetic metal in addition to Heisenberg exchange. The density functional theory and the tight-binding model calculations reveal that inversion symmetry breaking with spin–orbit coupling gives rise to the orbital-related correlation. Our study provides the experimental connection between the orbital physics and the spin–orbit-related phenomena, such as DMI