Magnetism of the A -site ordered perovskites CaCu3Cr4O12 and L

Abstract

The microscopic magnetic nature of the A-site ordered chromium perovskites CaCu 3 Cr 4 O 12 and LaCu 3 Cr 4 O 12 and their solid-solution system, Ca 1−x La x Cu 3 Cr 4 O 12 , with x = 0.2, 0.4, and 0.8, has been studied with muon spin rotation and relaxation (μ + SR) measurements down to 2 K using a powder sample. For CaCu 3 Cr 4 O 12 , μ + SR revealed the formation of static antiferromagnetic (AF) order below 122 K (=T N), although magnetization measurements showed a very small change at T N. Analyses of the internal magnetic field H int at the muon sites, predicted with first-principles calculations, suggested G-type AF order as a ground state. For LaCu 3 Cr 4 O 12 with T N = 225 K, μ + SR also supported the presence of a G-type AF ordered state, which was recently proposed based on neutron diffraction measurements. However, the ordered Cr moments were found to change the direction at around 10 K. For Ca 1−x La x Cu 3 Cr 4 O 12 , both T N and H int at 2 K increase monotonically with x.

High-Pressure Synthesis of a Novel Quadruple Perovskite Oxide AgCu₃Cr₄O₁₂

“…Therefore, we expect that the intrinsic magnetic property of AgCu 3 Cr 4 O 12 is probably antiferromagnetic like CaCu 3 Cr 4 O 12 and LaCu 3 Cr 4 O 12 rather than ferrimagnetism like CeCu 3 Cr 4 O 12 . 9,12) However, further study using microscopic probes such as µSR 9) is needed to elucidate the magnetic ground state for AgCu 3 Cr 4 O 12 .…”

“…The reference sample of CaCu 3 Cr 4 O 12 was synthesized according to the reference. 9,10) Synchrotron X-ray powder diffraction (SXRD) measurement was conducted at the BL02B2 beamline of SPring-8. 13) The powder sample obtained by crushing the pellet of AgCu 3 Cr 4 O 12 was filled into a Lindemann glass capillary with an inner diameter of 0.2 mm.…”

“…[1][2][3][4][5][6][7][8] The aliovalent A-site substitutions induce drastic changes in electronic properties by electron/hole-doping into the AAand/or B-site metals. CaCu 3 Cr 4 O 12 consisting of Cu 2+ (3d 9 ) and Cr 4+ (3d 2 ) ions, is an antiferromagnetic metal, 9,10) whereas LaCu 3 Cr 4 O 12 undergoes an antiferromagnetic transition simultaneously with charge transfer (3Cu (2+¤)+ + 4Cr (3.75¹0.75¤)+ 3Cu (3¹£)+ + 4Cr (3+0.75£)+ ) at 220 K, 11) followed by the ferrimagnetic metallic properties for Ce 4+ Cu 2+ 3 Cr 3.5+ 4 O 12 (T C = 333 K). 12) In their electron doping sequence, the electrons are primarily doped into the B-site Cr ions.…”