We investigated the magnetic and structural properties of the ferromagnetic pyroxene ${\text{NaCrGe}}_2{\text{O}}_6$ by superconducting quantum interference device magnetometry and powder neutron diffraction. This material is the only ferromagnetic member of the recently reported multiferroic pyroxene family $AM{\text{X}}_2{\text{O}}_6$ ($A=\text{Li},\text{Na}$; $M=\text{Fe},\text{Cr}$; $X=\text{Si},\text{Ge}$). Below $T_C=6\text{K}$, 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 ${\text{Cr}}^{3+}$ 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 $C{2}^{\prime }/c^{\prime }$. This symmetry does not allow a linear magnetoelectric effect. No structural phase transition was observed down to 1.8 K.

• Received 4 February 2009

DOI:https://doi.org/10.1103/PhysRevB.80.024402