Structural transformation induced by magnetic field and "colossal-like" magnetoresistance response above 313 K in MnAs
Physical Review Letters 90:9 (2003) 097203/4
Abstract:
MnAs is a commercially available material, intensively studied, both theoretically and experimentally, since the beginning of the last century. Interest in this compound could come up again as a consequence of new ideas and conjectures formulated during the last decade in connection with the study of the colossal magnetoresistance (CMR) response in Mn perovskites. Among these ideas is the invocation of a phase separation scenario for CMR manganese oxides and related materials that might be of particular relevance in systems, like MnAs, where first-order phase transitions occur.Structural transformation induced by magnetic field and "colossal-like" magnetoresistance response above 313 K in MnAs.
Phys Rev Lett 90:9 (2003) 097203
Abstract:
MnAs exhibits a first-order phase transition from a ferromagnetic, high-spin metal hexagonal phase to a paramagnetic, lower-spin insulator orthorhombic phase at T(C)=313 K. Here, we report the results of neutron diffraction experiments showing that an external magnetic field, B, stabilizes the hexagonal phase above T(C). The phase transformation is reversible and constitutes the first demonstration of a bond-breaking transition induced by a magnetic field. The field-induced phase transition is accompanied by an enhanced magnetoresistance of about 17% at 310 K. The phenomenon appears to be similar to that of the colossal magnetoresistance response observed in the Mn [corrected] perovskite family.Structural transformation induced by magnetic field and "Colossal-Like" magnetoresistance response above 313 K in MnAs (vol 90, art no 097203, 2003)
PHYSICAL REVIEW LETTERS 90:18 (2003) ARTN 189901
Charge ordered structure of magnetite Fe3 O4 below the Verwey transition
Physical Review B - Condensed Matter and Materials Physics 66:21 (2002) 2144221-21442215