Giant magnetoelectric effect in theJeff=12Mott insulatorSr<

Abstract

Our magnetic, electrical, and thermal measurements on single crystals of the J eff =1/ 2 Mott insulator, Sr 2 IrO 4 , reveal a giant magnetoelectric effect ͑GME͒ arising from a frustrated magnetic/ferroelectric state whose signatures are: ͑1͒ a strongly enhanced electric permittivity that peaks near an observed magnetic anomaly at 100 K, and ͑2͒ a large ͑ϳ100%͒ magnetodielectric shift that occurs near a metamagnetic transition. The GME hinges on a spin-orbit gapping of 5d bands rather than the magnitude and spatial dependence of magnetization, as traditionally accepted.

Crystal growth and intrinsic magnetic behaviour of Sr2IrO4

“…Sr214#4 shows another anomaly in the low temperature region (inset of Fig. 1(b)) similar to earlier data, based on which a transition to a differ- ent magnetic structure, possibly a non-coplanar structure that has a c-axis component, has been suggested 18,25 . However, these anomalies are clearly absent in Sr214#1.…”

“…Whereas Sr214#1 with the highest saturated moment shows a sharp peak at T = 215 K, Sr214#4 shows a broad hump peaked at a much lower temperature T = 175 K. Two anomalies are found in Sr214#2 and Sr214#3, suggesting coexistence of the two features seen in Sr214#1 and Sr214#4. It is noteworthy that previously published results share more resemblance to the broad profile of Sr214#4 rather than the sharp profile of Sr214#1 18,25 . Sr214#4 shows another anomaly in the low temperature region (inset of Fig.…”

“…Therefore, we believe that the magnetic behavior reported above for Sr214#1 is representative of the clean, ideal phase of Given that samples that were exposed to high temperature for longer time have lower sample quality, we further investigated the effect of prolonged exposure at 1300 • C (Sr214−δ#1, see table II). This sample showed significantly reduced magnetic ordering temperature, and a down turn in the M (T ) curve below ∼50 K. Most of the earlier data on Sr 2 IrO 4 show such down turn in the M (T ) curve 18,25 . Our EDX measurements indicate that Sr214−δ#1 is deficient in oxygen (see table I).…”

“…Moreover, we note that previous studies on the parent Sr 2 IrO 4 and its sister compounds have shown significant variations in the magnetic properties even without doping, likely reflecting different defect concentrations 2,4,18,[22][23][24][25][26][27][28][29] . For example, the sizable c-axis component of the uniform magnetic susceptibility is not understood and seems incompatible with the known magnetic structure of Sr 2 IrO 4 .…”

Spin-orbit tuned metal-insulator transitions in single-crystal Sr2Ir1−xRhxQi1, Korneta2, Li3 et al. 2012Phys. Rev. BSelf Cite116101440View full textAdd to dashboardCite

“…elsewhere [6, [8][9][10]. The size of the single crystals is as large as 1.0 x 1.0 x 0.2 cm 3 (see Fig.1d).…”