Magnetization Dynamics of Materials for Spintronics and Magnonic Devices : Investigation Using Current and Light

In depth understanding of magnetization dynamics in Ferromagnetic thin film with structure inversion asymmetry is important for developing advanced spintronics and magnonic devices. For applications in magnetic memory devices, emerging device concepts based on domain wall motion and skyrmionic lattice have been proposed, which aim to use heavy metal (HM)/ultrathin ferromagnet (FM)/Oxide heterostructures. In such heterostructures, due to the strong spin-orbit interaction in HM layer, perpendicular magnetic anisotropy [1], spin Hall effect [2], and interfacial Dzyaloshinskii-Moriya interaction (IDMI) [3] are manifested. In this talk, the detailed magnetic properties (saturation magnetization, magnetic dead layer thickness, and interface anisotropy) in HM/FM/Oxide for various HM layer will be discussed. Magnetic inhomogeneity originating due to interfacial roughness in these heterostructures as investigated using Brillouin light scattering (BLS) technique will be presented [4]. Subsequently, the imprint of pure IDMI on the spinwave spectra of these heterostructures will be shown. Spin Hall effect driven modulation of damping and its detection using all optical excitation and detection technique, namely, time resolved magneto-optical Kerr effect will be discussed [5]. 
In the later part of the talk I shall discuss about the microwave emission from spin transfer nano-oscillator which has received attention because of its ability to fit in various application (e.g. microwave assisted magnetic recording, on chip communication etc). The result of microwave emission from Heusler alloy based spin valve nanopillar device will be presented. It will be shown that significantly narrow line width in the microwave emission from these devices can be obtained by reducing the nonlinear phase noise in the devices [6]. 
[1] Jaivardhan Sinha, et al. Appl. Phys. Lett. 102, 242405 (2013). 
[2] J. Kim, Jaivardhan Sinha, M. Hayashi, M. Yamanouchi, S. Fukami, T. Suzuki, S. Mitani, 
     and H. Ohno, Nature Materials 12, 240 (2013). 
[3] J. Torrejon, J. Kim, Jaivardhan Sinha, S. Mitani, M. Hayashi, M. Yamanouchi, H. Ohno, 
     Nature Comm. 5, 4655 (2014). 
[4] Jaivardhan Sinha et al RSC advances 5, 57815 (2015) 
[5] A. Ganguly et al Appl. Phys. Lett. 105, 112409 (2014). 
[6] Jaivardhan Sinha et al Appl. Phys. Lett. 99, 162508 (2011).