APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014;
Denver, Colorado
Session F40: Invited Session: New Magnetoresistance in Metal/Magnetic Insulator Heterostructures
8:00 AM–10:24 AM,
Tuesday, March 4, 2014
Room: Mile High Ballroom 2B-3B
Sponsoring
Unit:
GMAG
Chair: Sufeng Zhang, Arizona University
Abstract ID: BAPS.2014.MAR.F40.3
Abstract: F40.00003 : Hybrid magnetoresistance in the proximity of a ferromagnet
9:12 AM–9:48 AM
Preview Abstract
Abstract
Author:
Chia-Ling Chien
(Johns Hopkins University)
A new type of magnetoresistance (MR) effect has recently been observed in
nominally nonmagnetic metal (Pt) thin films in contact with either a
ferromagnetic (FM) insulator such as yttrium iron garnet
(YIG),\footnote{H. Nakayama \textit{et al., }Phys. Rev. Lett. \textbf{110}, 206601(2013).} or a FM metal,\footnote{Y. M. Lu \textit{et al,,} Phys. Rev. B \textbf{87}, 220409(R) (2013).} such as permalloy (Py).
The resistivities with in-plane magnetic fields parallel ($\rho
_{\mathrm{\parallel }})$ and transverse ($\rho_{\mathrm{T}})$ to a
current and a perpendicular field ($\rho_{\mathrm{\bot }})$ at room
temperature show the behavior of $\rho_{\mathrm{\bot }}\approx \rho
_{\mathrm{\parallel }}$\textgreater $\rho_{\mathrm{T}}$, distinctively
different from all other known MR effects, including the well-known
anisotropic MR in FMs of $\rho_{\mathrm{\parallel }}$\textgreater $\rho
_{\mathrm{T}}\approx \rho_{\mathrm{\bot }}$. The key question is
whether the new MR is the proposed spin Hall MR (SMR) based on spin current
conversion in Pt, or due to magnetic proximity effects (MPE), for which Pt
is highly susceptible when in contact with a FM. Recent experiments show
that the characteristics of $\rho_{\mathrm{\bot }}\approx \rho
_{\mathrm{\parallel }}$\textgreater $\rho_{\mathrm{T}}$, for which the
SMR theory accounts, do not hold at low temperatures nor at different
magnetic fields. Furthermore, the new MR persists even after altering the
Pt/YIG interface thereby blocking the spin current.\footnote{B. F. Miao \textit{et al.,} Phys. Rev. Lett. \textbf{111}, 066602 (2013).} The
feature of new MR can also be reproduced when Pt is in contact with a
non-magnetic insulator doped with a few percent of Fe impurities. These
results show that the new MR is probably due to both spin current and MPE.
Through tuning the YIG surface and the insertion of other layers between Pt
and YIG, we are able to separate the two contributions of spin current and
MPE of the new hybrid MR.
This work, in collaboration with S. Y. Huang, D. Qu (JHU) B. F. Miao (JHU
and Nanjing University), Y. M. Lu and J. W. Cai (Institute of Physics,
Chinese Academy of Sciences), has been supported in part by NSF DMR1262253.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2014.MAR.F40.3