Magnetic properties of Ba2Cu3O4Cl2 single crystals

Ferromagnetic Moment and Spin Rotation Transitions in Tetragonal AntiferromagneticSr2Cu3O4Chou1, Aharony2, Birgeneau3 et al. 1997Phys. Rev. Lett.667710View full textAdd to dashboardCite

“…1) [7]. Similarly to other lamellar cuprates, neutron scattering experiments find Cu I antiferromagnetic (AFM) order below T N,I ഠ 380 K. In addition, the Cu II's exhibit AFM order below T N,II ഠ 40 K [4,6,8] We have focused on Sr 2 Cu 3 O 4 Cl 2 , for which it is possible to grow large single crystals by slow cooling from a melt containing CuO as flux. Small crystals, ϳ6 mm 3 7 mm 3 0.5 mm, with the c axis (normal to the Cu 3 O 4 layer) perpendicular to the large face are used for measurements of M͑H͒ with a quantum design SQUID magnetometer at H , 5.5 T. High-resolution synchrotron x-ray powder diffraction measurements show that the crystal remains tetragonal (space group I4͞mmm) for temperatures 15 , T , 550 K, with lattice contants a 5.457 Å and c 12.52 Å for T , 50 K. (The effects of the lower magnetic symmetry are negligible.…”

“…Recently, attention has focused on "234" variants of the cuprates, Sr 2 Cu 3 O 4 Cl 2 and Ba 2 Cu 3 O 4 Cl 2 [4][5][6]. These materials have an additional Cu ion (denoted by Cu II) at the center of every second plaquette of the CuO 2 lattice (made of Cu I's), creating two interpenetrating square lattices of Cu ions (see Fig.…”

Weak ferromagnetism in Ba2Cu3−xCoxO4Cl2 () and Ba2−ySryCu3O4Cl2 ()

“…The Cu 3 O 4 layer contains two types of Cu sites: two-thirds of them (denoted by Cu A ) have an octahedral coordination with four squareplanar oxygen ions in the basal plane and two chlorine ions at the apices, and the other one-third Cu ions (Cu B ) are surrounded only by four squareplanar oxygen ions as shown in Fig. 1b Previously, two magnetic transitions were observed for Ba 2 Cu 3 O 4 Cl 2 ; one is at 330 K (denoted by T H ) and the other is at 30 K (T L ) [2]. It is believed that at T H only the Cu A spins order, in a canted antiferromagnetic arrangement with a small in-plane ferromagnetic moment, and that at T L both Cu A and Cu B spins are ordered antiferromagnetically [2][3][4].…”

“…1b Previously, two magnetic transitions were observed for Ba 2 Cu 3 O 4 Cl 2 ; one is at 330 K (denoted by T H ) and the other is at 30 K (T L ) [2]. It is believed that at T H only the Cu A spins order, in a canted antiferromagnetic arrangement with a small in-plane ferromagnetic moment, and that at T L both Cu A and Cu B spins are ordered antiferromagnetically [2][3][4]. Between T H and T L , a relatively large paramagnetic susceptibility was observed, which might be due to the existence of free Cu B spins.…”

Possibility of soft-matter effects in solids

“…We consider the model FM+AFM multiferroic [3][4][5] whose magnetic structure consists of two weakly coupled subsystems, AFM, and FM, localized on different types of magnetic ions CI and CII, as shown in figure 3. A FM subsystem is unambiguously described by a magnetization vector M F and an AFM subsystem is described by two vectors: an AFM vector L = (S 1 − S 2 + S 3 − S 4 )/4 and a FM vector M = j S j /4.…”