Evidence for an orbital moment in the superconducting state of URu$_2$Si$_2$
ORAL
Abstract
URu$_2$Si$_2$ was suggested to be a chiral \emph{d}-wave superconductor with a $k_z (k_x \pm ik_y)$ orbital component for the Cooper pair wave-function. This state breaks time-reversal symmetry due to the orbital moment associated with this pair wave-function. Here, we report torque magnetometry in URu$_2$Si$_2$ at high fields and very low temperatures revealing a change in the sign of the magnetic hysteresis for $H \rightarrow H_{c2}$, and for angles $15^{\circ}$ away from the \emph{ab}-plane, i.e. from a clear diamagnetic response dominated by the pinning of vortices to a state with a much smaller but paramagnetic-like hysteretic response which \emph{disappears} at $H_{c2}$. If diamagnetism results from screening super-currents, we conclude that this hysteretic paramagnetic response must result from super-currents circulating in the opposite sense which generate an effective moment as expected for a chiral superconductor.
*Supported by DOE-BES through award DE-SC0002613.
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Authors
Gang Li
Physics Dept., Univ. of Michigan
National High Magneti Field Lab
National High Magnetic Field Lab
Qiu Zhang
National High Magnetic Field Laboratory, Tallahassee, FL, USA
National High Magneti Field Lab
National High Magnetic Field Lab
Daniel Rhodes
National High Magneti Field Lab
National High Magnetic Field Lab
Bin Zheng
National High Magneti Field Lab
National High Magnetic Field Lab
Pallab Goswami
National High Magnetic Field Lab
National High Magnetic Field Laboratory and Florida State University
National High Magnetic Field Laboratory
P. Tobash
Los Alamos National Lab
Filip Ronning
Los Alamos National Laboratory
Los Alamos National Lab
Joe Thompson
Los Alamos National Laboratory
Los Alamos National Lab
MPA-CMMS, LANL
Eric Bauer
Los Alamos National Laboratory
Los Alamos National Lab
L. Balicas
National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
