APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016;
Baltimore, Maryland
Session H2: Emergent Topological Phenomena in Pyrochlore Iridates II
2:30 PM–5:30 PM,
Tuesday, March 15, 2016
Room: Ballroom II
Sponsoring
Units:
DCMP DMP GMAG
Chair: Zhi-Xun Shen, Stanford Univ
Abstract ID: BAPS.2016.MAR.H2.1
Abstract: H2.00001 : Metal-insulator transitions of bulk and domain-wall states in pyrochlore iridates.
2:30 PM–3:06 PM
Preview Abstract
Abstract
Author:
Kentaro Ueda
(RIKEN CEMS)
A family of pyrochlore iridates
$R_{\mathrm{2}}$Ir$_{\mathrm{2}}$O$_{\mathrm{7}}$ offers an ideal platform to
explore intriguing phases such as topological Mott insulator and Weyl
semimetal [1]. Here we report transport and spectroscopic studies on the
metal-insulator transition (MIT) induced by the modulations of effective
electron correlation and magnetic structures, which is finely tuned by
external pressure, chemical substitutions ($R \quad =$
Nd$_{\mathrm{1-}}_{x}$Pr$_{x}$ and Sm$_{y}$Nd$_{\mathrm{1-}}_{y})$, and
magnetic field. A reentrant insulator-metal-insulator transition is observed
near the paramagnetic insulator-metal phase boundary reminiscent of a
first-order Mott transition for $R \quad =$ Sm$_{y}$Nd$_{\mathrm{1-}}_{y}$
compounds ($y$\textasciitilde 0.8). The metallic states on the magnetic domain
walls (DWs), which are observed for $R =$ Nd in real space [2] as well as in
transport properties [3], is simultaneously turned into the insulating one.
These findings imply that the DW electronic state is intimately linked to
the bulk states. For the mixed $R \quad =$ Nd$_{\mathrm{1-}}_{x}$Pr$_{x}$
compounds, the divergent behavior of resistivity with antiferromagnetic
order is significantly suppressed by applying a magnetic field along [001]
direction [4]. It is attributed to the phase transition from the
antiferromagnetic insulating state to the novel Weyl (semi-)metal state
accompanied by the change of magnetic structure. The present study combined
with experiment and theory suggests that there are abundant exotic phases
with physical parameters such as electron correlation and Ir-5$d$ magnetic
order pattern.
Work performed in collaboration with J. Fujioka, B.-J. Yang, C. Terakura, N.
Nagaosa, Y. Tokura (University of Tokyo, RIKEN CEMS), J. Shiogai, A.
Tsukazaki, S. Nakamura, S. Awaji (Tohoku University).
$^{\mathrm{1}}$This work was supported by JSPS FIRST Program and
Grant-in-Aid for Scientific Research (Grants No. 80609488 and No. 24224009).
[1] W. Witczak-Krempa, G. Chen, Y. B. Kim, and L. Balents, Annu. Rev.
Condens. Matter Phys. \textbf{5}, 57 (2014).
[2] Eric Yue Ma, Yong-Tao Cui, Kentaro Ueda, Shujie Tang, Kai Chen,
Nobumichi Tamura, Phillip M. Wu, Jun Fujioka, Yoshinori Tokura, and Zhi-Xun
Shen, Science \textbf{350}, 538 (2015).
[3] K. Ueda, J. Fujioka, Y. Takahashi, T. Suzuki, S. Ishiwata, Y. Taguchi,
M. Kawasaki, and Y. Tokura, Phys. Rev. B \textbf{89}, 075127 (2014).
[4] K. Ueda, J. Fujioka, B.-J. Yang, J. Shiogai, A. Tsukazaki, S. Nakamura,
S. Awaji, N. Nagaosa, and Y. Tokura, Phys. Rev. Lett. \textbf{115}, 056402
(2015).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2016.MAR.H2.1