APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014;
Denver, Colorado
Session F52: Focus Session: New and Improved Superconducting Materials
8:00 AM–11:00 AM,
Tuesday, March 4, 2014
Room: Mile High Ballroom 1F
Sponsoring
Unit:
DMP
Chair: Eric Palm, National High Magnetic Field Laboratory
Abstract ID: BAPS.2014.MAR.F52.4
Abstract: F52.00004 : Superconductivity in BiS$_2$-based compounds*
8:36 AM–9:12 AM
Preview Abstract
Abstract
Author:
Duygu Yazici
(University of California, San Diego)
Polycrystalline samples of $Ln$O$_{0.5}$F$_{0.5}$BiS$_2$ ($Ln$ = La, Ce, Pr, Nd, Yb) were synthesized by solid-state reaction. These compounds form in a tetragonal structure with space group $P4/nmm$ conforming to the CeOBiS$_2$ crystal structure. Electrical resistivity, magnetic susceptibility and specific heat measurements were performed on all of the samples. All of the compounds exhibit superconductivity in the range 1.9 K - 5.4 K, and the YbO$_{0.5}$F$_{0.5}$BiS$_2$ sample was also found to exhibit magnetic order (probably antiferromagnetic order) at $\sim$2.7 K that appears to coexist with superconductivity below 5.4 K [1]. Electron-doping appears to induce superconductivity in the BiS$_2$-based superconductors as partial substitution of F for O is necessary to observe superconductivity. This was further demonstrated in a study where trivalent La$^{+3}$ was partially substituted with tetravalent Th$^{+4}$, Hf$^{+4}$, Zr$^{+4}$, and Ti$^{+4}$, all of which induced superconductivity [2]. We also observed that substitution of divalent Sr$^{+2}$ for La$^{+3}$ (hole doping) does not induce superconductivity [2].
Electrical resistivity measurements were also performed under applied pressure on $Ln$O$_{0.5}$F$_{0.5}$BiS$_2$ ($Ln$ = La, Ce, Pr, Nd) up to $\sim$3 GPa and down to 1 K. These studies revealed a universal behavior where the systems are tuned away from semi-conducting behavior towards metallic behavior. The superconducting states were stabilized by applied pressure, so that $T_c$ ~increased in all of the rare earth members listed. At a critical pressure $P_c$, $T_c$ increases rapidly from a low $T_c$ phase to a distinct high $T_c$ phase, after which additional pressure no longer suppressed the semiconducting behavior in the normal state [3,4]. In addition, the metallization of NdO$_{0.5}$F$_{0.5}$BiS$_2$ also occurs at $P_c$.\\[4pt]
This work was performed in collaboration with M. B. Maple, K. Huang, B. D. White and C. T. Wolowiec.
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[1] Yazici et al, Philos. Mag. 93, 673, (2012).\\[0pt]
[2] Yazici et al, Phys. Rev. \textbf{B} 87, 174512, (2013).\\[0pt]
[3] Wolowiec et al, Phys. Rev. \textbf{B} 88, 064503, (2013).\\[0pt]
[4] Wolowiec et al, Journal of Physics: Condensed Matter 25, 422201, (2013).
*Research was supported by the US AFOSR MURI FA9550-09-1-0603, US DOE DE-FG02-04-ER46105 and NNSA DE-NA0001841.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2014.MAR.F52.4