Complex magnetic ordering inCeGe1.76studied by neutron diffraction

Abstract

Neutron diffraction measurements on a single crystal of CeGe1.76 reveal a complex series of magnetic transitions at low temperature. At TN ≈ 7 K, there is a transition from a paramagnetic state at higher temperature to an incommensurate magnetic structure characterized by a magnetic propagation vector (0 0 τ ) with τ ≈ 1 4 and the magnetic moment along the a axis of the orthorhombic unit cell. Below TLI ≈ 5 K, the magnetic structure locks in to a commensurate structure with τ = 1 4 and the magnetic moment remains along the a axis. Below T ⋆ ≈ 4 K, we find additional half-integer and integer indexed magnetic Bragg peaks consistent with a second commensurately ordered antiferromagnetic state.