High-pressure structural stability of multiferroic hexagonalRMnO3(R=Y, Ho, Lu)

Abstract

Structural changes in REMnO 3 (RE= Y, Ho, Lu) under high pressure were examined by synchrotron x-ray diffraction methods at room temperature. Compression occurs more readily in the ab plane than along the c-axis. With increased pressure, a pressure-induced hexagonal to orthorhombic phase transition was observed starting at ~ 22 GPa for Lu(Y)MnO 3 . When the pressure is increased to 35 GPa, a small volume fraction of Lu(Y)MnO 3 is converted to the orthorhombic phase and the orthorhombic phase is maintained on pressure release. High pressure IR absorption spectroscopy and Mn K-edge near edge x-ray absorption spectroscopy confirm that the hexagonal P6 3 cm structure is stable below ~20 GPa and the environment around Mn ion is not changed. Shifts in the unoccupied p-band density of states with pressure are observed in the Mn K-Edge spectra. A schematic pressure-temperature phase diagram is given for the small ion REMnO 3 system.

Strong-coupling superconductivity in LiB2C2 trilayer films

“…In order to dope holes without introducing lattice distortion, replacing partially carbons by borons was proposed [18,19]. In particular, based on first-principles calculations, we predicted that both Li 3 B 4 C 2 and Li 2 B 3 C could become superconducting above 50 K [19]. A similar compound Li 4 B 5 C 3 was also predicted to be a superconductor at 16.8 K [20].…”

Doping effects on trimerization and magnetoelectric coupling of single crystal multiferroic (Y,Lu)MnO3

“…In general,  has the temperature-independent value of 1 -3 for most common magnetic materials although it can become much larger and/or displays unusual temperature dependence for certain materials [32]. Using the reported bulk modulus value of K = 1.0  10 11 kg/mT 2 for YMnO 3 [33,34], we have calculated the Grüneisen parameter as shown in Fig. 4.…”

The Magnetic Phase Transition and Universality Class of h-YMnO3 and h-(Y0.98Eu0.02)MnO3 Under Zero and Applied Pressure

“…Considering that the effect of pressure is stronger in the plane, because the relative change of the lattice constant a is larger than the relative change of the constant c [34], a stronger effect on the in-plane couplings is also expected. This is also in accordance with the observation that the magnon-phonon coupling as observed in earlier experiments [23] can be solely modelled by a modulation of the in-plane couplings, the same modulation that takes place by the static change of the distance between the magnetic ions upon application of pressure.…”