Phase-Sensitive Observation of a Spin-Orbital Mott State in Sr2IrO4
B. J. Kim,1,2*
H. Ohsumi,3
T. Komesu,3
S. Sakai,3,4
T. Morita,3,5
H. Takagi,1,2*
T. Arima3,6
Measurement of the quantum-mechanical phase in quantum matter
provides the most direct manifestation of the underlying abstract
physics. We used resonant x-ray scattering to probe the relative
phases of constituent atomic orbitals in an electronic wave
function, which uncovers the unconventional Mott insulating
state induced by relativistic spin-orbit coupling in the layered
5
d transition metal oxide Sr
2IrO
4. A selection rule based on
intra-atomic interference effects establishes a complex spin-orbital
state represented by an effective total angular momentum = 1/2
quantum number, the phase of which can lead to a quantum topological
state of matter.
2 Magnetic Materials Laboratory, RIKEN Advanced Science Institute, Wako 351-0198, Japan.
3 RIKEN SPring-8 Center, Sayo 679-5148, Japan.
4 Department of Physical Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
5 Department of Physics, Kwansei-Gakuin University, Sanda 669-1337, Japan.
6 Institute of Multidisciplinary Research for Adavanced Materials, Tohoku University, Sendai 980-8577, Japan.
* To whom correspondence should be addressed. E-mail: bjkim6{at}gmail.com (B.J.K.); htakagi{at}k.u-tokyo.ac.jp (H.T.)
