Weak ferromagnetism, metal-to-nonmetal transition, and negative differential resistivity in single-crystalSr2IrO4

Charge density wave formation accompanying ferromagnetic ordering in quasi-one-dimensional BaIrO3

“…The Ir moment is much lower than expected for the low spin S 1=2; 2 T 2g state of Ir 4ϩ (5d 5 ) which has degenerate d xz and d yz orbitals and an excited half filled d xy orbital, but both T C and the moment value are in substantial agreement with the results of Lindsay et al [4] for polycrystalline material. Similar low Ir moments are found for ferromagnetic Sr 2 IrO 4 T C 250 K; m eff 0:04m B =Ir as well as for CaIrO 3 and Ca 2 IrO 4 [7,12].…”

“…However, the ferromagnetism at T c3 175 K in BaIrO 3 [4] appears to be accompanied by and possibly driven by a collective electronic excitation or at least partial gapping of the Fermi surface. This demonstrates once again the strong coupling between spin and charge in the heavy (4d-and 5d-based) TMOs [5][6][7]. BaIrO 3 has a highly anisotropic quasi-one-dimensional structure [8][9][10] and this gives rise, in our single crystal samples, to large anisotropy of r(T), the electrical resistivity, with the quasi-one-dimensional axis, the c-axis, having much lower resistivity.…”

“…The striking non-ohmic "S" shape illustrates current controlled negative differential resistivity [14] (NDR) over a wide range of currents and temperatures, but restricted to T Ͻ T C3 : We stress this as a bulk effect, similar in that respect to the Gunn effect, which, however, displays "N" shaped, voltage controlled NDR I-V characteristics [15]. "S" NDR has been found in three other systems: Ca 3 Ru 2 O 7 [16], Sr 2 IrO 4 [7], and Ca 2 IrO 4 [7] also below their respective magnetic ordering temperatures. The non-hysteretic large main feature of non-linearity of the I-V characteristics may be due to an electrothermal effect which can occur in systems with dr T =dT Ͻ 0 if the heat sinking to ambient temperature is insufficient to remove joule heating.…”

Interplay between Hund’s Coupling and Spin–Orbit Interaction on Elementary Excitations in Sr2IrO4

“…For this reason, much attention has recently been paid to Ir oxides such as Sr 2 IrO 4 1-8 and Na 2 IrO 3 . [9][10][11][12] In particular, we focus on Sr 2 IrO 4 , which consists of two-dimensional IrO 2 layers showing structural similarity to the parent compound of high-T C cuprate La 2 CuO 4 , and exhibits a canted antiferromagnetic (AFM) order below 230 K. [1][2][3] The energy of the e g orbitals is estimated about 2 eV higher than that of the t 2g orbitals due to the large crystal field. Five 5d electrons are occupied per Ir atom, and one hole is sitting in the t 2g orbitals.…”

Noncollinear versus collinear description of the Ir-based one-t2g-hole perovskite-related compounds:SrIrO3andSr2Lado1, Pardo2 2015Phys. Rev. B12580View full textAdd to dashboardCite

“…23 Some papers indicate the ordered moment can be produced via slight canting of the otherwise AF moments. [24][25][26][27] The canting angle (see Fig.…”