PRIMARY ROLE OF THE STRUCTURAL PHASE-TRANSITION IN THE STRONGLY COUPLED STRUCTURE AND MAGNETISM OF LA0.835SR0.165MNO3 SINGLE-CRYSTAL

We report a neutron diffraction investigation of the role of pressure on the strong coupling between the structural and ferromagnetic phase transitions in La0.835Sr0.165MnO3. The results are summarized in the f orm of a pressure-temperature phase diagram and reveal the dominant ch aracter of the structural changes with respect to the magnetic transit ions, which results in a broad metastable area around the crossing poi nt of the structural and magnetic phase transitions. The phase diagram contains a number of extremely unusual features including the pressur e independence of the Curie temperature in the orthorhombic phase, a r eentrance of the rhombohedral phase at low temperatures, and a change of the type of the magnetic phase transition from second order to firs t order due to the strong coupling between the structural and the magn etic properties of this material.