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Structural, magnetic, and magnetocaloric properties of the double perovskite La2CoMnO6 single crystals are investigated. The nature of the magnetic phase transition is analysed in terms of magnetic measurements and the Landau theory. The proportion of cationic order and the Co/Mn oxidation states were identified from the effective magnetic moment and Raman spectroscopy studies. La2CoMnO6 single crystals exhibit a significant refrigerant capacity. For a magnetic field change of 5 T, a refrigerant capacity of 222 J/kg is obtained. The magnetocaloric performance of La2CoMnO6 single crystals in the vicinity of the ferromagnetic-paramagnetic transition region (TC=170K) is discussed and compared with that of a polycrystalline sample. [ABSTRACT FROM AUTHOR]

Millimeter size single crystals of double-perovskite La2NiMnO6 were grown by the high-temperature solution growth method. The magnetic measurements and polarized Raman spectra between 5 and 350 K provide evidence that the crystals have a high degree of Ni2+/Mn4+ ordering, a small amount of lattice defects, and the highest Tc=288 K reported so far for ferromagnetic double perovskites. At a microscopic level, the crystals are heavily twinned, and the effect of twinning on the Raman spectra is analyzed in detail. [ABSTRACT FROM AUTHOR]

A well-controlled coupled behavior in magnetoelectric materials at room temperature remains challenging. We demonstrate that the self-ordered A2B'B"O6 (e.g., A=La, B'=Mn, and B"=Ni) double perovskites provide a unique alternative opportunity to control and/or to induce such behavior in oxides. Herein, we outline and discuss the various challenges and bottleneck issues related to this class of materials. [ABSTRACT FROM AUTHOR]

In the quest for novel magnetoelectric materials, we have stabilized La3BAlMnO9 (B=Co or Mn) in thin film form.We studied the influence of the growth parameters that promote B/Al/Mn ordering in the pseudocubic unit cell and their impact on the functional and coupled properties. Compared to La2BMnO6, it is observed that the insertion of AlO6 octahedra between BO6 and MnO6 suppresses significantly strength of the superexchange interaction and coupled properties. [ABSTRACT FROM AUTHOR]

We present the details of growth parameters which promote the cationic ordering in multiferroic A2CoMnO6 (A=La or Bi) thin films grown on SrTiO3 (001). Our study manifest that well-ordered Co/Mn states can be achieved at relatively high temperature and oxygen partial pressure. Structural, magnetic, and magnetodielectric properties of these films are studied. The importance and influence of Co/Mn ordering and the role of A-type cations on the physical properties of A2CoMnO6 films are elucidated. [ABSTRACT FROM AUTHOR]