Magnetoelastic and thermal effects in the BiMn2O5 lattice: a high-resolution x-ray diffraction study

E. Granado; M. S. Eleoterio; A. F. Garcia-Flores; J. A. Souza; E. I. Golovenchits; V. A. Sanina

doi:10.1103/PhysRevB.77.134101

paper

Magnetoelastic and thermal effects in the BiMn2O5 lattice: a high-resolution x-ray diffraction study

arXiv:0711.4742 · doi:10.1103/PhysRevB.77.134101

Abstract

High-resolution synchrotron x-ray diffraction measurements were performed on single crystalline and powder samples of BiMn2O5. A linear temperature dependence of the unit cell volume was found between T_{N}=38 $K an d 100 K, s ug g es t in g t ha t a l o w - e n er g y l a tt i cee x c i t a t i o nma y b er es p o n s ib l e f or t h e l a tt i cee x p an s i o nin t hi s t e m p er a t u r er an g e . B e tw ee n T * 65 K an d T_{N}, a l l l a tt i ce p a r am e t er ss h o w e d in c i p i e n t ma g n e t oe l a s t i ce f f ec t s, d u e t os h or t - r an g es p in cor r e l a t i o n s . A nani so t r o p i cs t r aina l o n g t h e a - d i r ec t i o n w a s a l soo b ser v e d b e l o w T * . B e l o w T_{N}, a r e l a t i v e l y l a r g eco n t r a c t i o n o f t h e a - p a r am e t er f o l l o w in g t h es q u a r eo f t h e a v er a g es u b l a tt i ce ma g n e t i z a t i o n o f M n w a s f o u n d, in d i c a t in g t ha t a seco n d - or d er s p inhami l t o niana cco u n t s f or t h e ma g n e t i c in t er a c t i o n s a l o n g t hi s d i r ec t i o n . O n t h eo t h er han d, t h e m or eco m pl e x b e ha v i or s f o u n df or$ b $an d$ c$ suggest additional magnetic transitions below T_{N} and perhaps higher-order terms in the spin hamiltonian. Polycrystalline samples grown by distinct routes and with nearly homogeneous crystal structure above T_{N} presented structural phase coexistence below T_{N}, indicating a close competition amongst distinct magnetostructural states in this compound.

23 pages, 7 figures

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