Magnetic and crystal structures of the one-dimensional ferromagnetic chain pyroxene NaCrGe2 O6

Abstract

We investigated the magnetic and structural properties of the ferromagnetic pyroxene NaCrGe2 O6 by superconducting quantum interference device magnetometry and powder neutron diffraction. This material is the only ferromagnetic member of the recently reported multiferroic pyroxene family AM X2 O6 (A=Li,Na; M=Fe,Cr; X=Si,Ge). Below TC =6K, the magnetic structure is characterized by one-dimensional magnetic chains with spins aligned along the c axis of the monoclinic cell. The magnetic moment of Cr3+ is significantly reduced by about 25%. We show that this is likely the result of the low dimensionality of the system. The associated magnetic space group is C 2′/c′. This symmetry does not allow a linear magnetoelectric effect. No structural phase transition was observed down to 1.8 K. © 2009 The American Physical Society.