Large Manipulation of Ferrimagnetic Curie Temperature by A-Site Chemical Substitution in ACuFeReO (A = Na, Ca, and La) Half Metals.

CaCuFeReO and LaCuFeReO quadruple perovskite oxides are well known for their high ferrimagnetic Curie temperatures and half-metallic electronic structures. By A-site chemical substitution with lower valence state Na, an isostructural compound NaCuFeReO with both A- and B-site ordered quadruple perovskite structures in -3 symmetry was prepared using high-pressure and high-temperature techniques. The X-ray absorption study demonstrates the valence states to be Cu, Fe, and Re.

Observation of Enhanced Long-Range Ferromagnetic Order in B-Site Ordered Double Perovskite Oxide CdCrSbO.

A B-site ordered double perovskite oxide CdCrSbO was synthesized under high-pressure and high-temperature conditions. The compound crystallizes to a monoclinic structure with a space group of 2/. The charge configuration is confirmed to be that of Cd/Cr/Sb.

High-Pressure Synthesis of Semiconducting PbCuMnO with Near-Room-Temperature Ferrimagnetic Order.

A transition-metal oxide of PbCuMnO was prepared at 1523 K and 10 GPa. An A-site-ordered quadruple perovskite structure with the space group 3̅ is assigned for this compound. Based on bond-valence-sum calculations and X-ray absorption spectroscopy, the charge combination is determined to be PbCuMnO.

Exceptional Magnetocaloric Responses in a Gadolinium Silicate with Strongly Correlated Spin Disorder for Sub-Kelvin Magnetic Cooling.

The development of magnetocaloric materials with a significantly enhanced volumetric cooling capability is highly desirable for the application of adiabatic demagnetization refrigerators in confined spatial environments. Here, the thermodynamic characteristics of a magnetically frustrated spin-7/2 Gd[SiO]O is presented, which exhibits strongly correlated spin disorder below ≈1.5 K.

High-Pressure Synthesis of Quadruple Perovskite Oxide CaCuCrReO with a High Ferrimagnetic Curie Temperature.

An AA'BB'O-type quadruple perovskite oxide of CaCuCrReO was synthesized at 18 GPa and 1373 K. Both an A- and B-site ordered quadruple perovskite crystal structure was observed, with the space group -3. The valence states are verified to be CaCuCrReO by bond valence sum calculations and synchrotron X-ray absorption spectroscopy.

Robust Crystal Phase Separation with Distinct Charge, Orbital, and Spin Orders in AgMnO.

An AA'BO-type A-site-ordered quadruple perovskite oxide AgMnO was prepared by high-pressure and high-temperature methods. At room temperature, the compound crystallizes into a cubic 3̅ symmetry with a charge distribution of AgMnMnO. With the temperature decreasing to ≈ 180 K, the compound undergoes a structural phase transition toward a monoclinic 2/ symmetry, giving rise to a B-site charge- and orbital-ordered AgMnMnMnO phase.

CaCuMnTeO: An Intrinsic Ferrimagnetic Insulator Prepared Under High Pressure.

CaCuMnTeO was synthesized using high-temperature and high-pressure conditions. The compound possesses an A- and B site ordered quadruple perovskite structure in 3̅ symmetry with the charge combination of CaCuMnTeO. A ferrimagnetic phase transition originating from the antiferromagnetic interaction between A' site Cu and B site Mn ions is found to occur at ≈ 100 K.

High-pressure single crystal growth and magnetoelectric properties of CdMnO.

The concurrent presence of large electric polarization and strong magnetoelectric coupling is quite desirable for potential applications of multiferroics. In this paper, we report the growth of CdMnOsingle crystals by flux method under a high pressure of 8 GPa for the first time. An antiferromagnetic (AFM) order with a polar magnetic point group is found to occur at the onset temperature of= 88 K (AFM1 phase).