Magnetic properties of NdCrGeTiO having spin- antiferromagnetic alternating chains of Cr spins and dimers of Nd moments

長谷 正司*; 池田 真奈美*; 萩原 雅人; 久保田 正人

Journal of Magnetism and Magnetic Materials, 653, p.174193_1 - 174193_7, 2026/09

https://doi.org/10.1016/j.jmmm.2026.174193

We investigated the magnetic properties of NdCrGeTiO, in which Cr spins and Nd moments form spin- antiferromagnetic (AFM) alternating chains and dimers, respectively. The ranges in which an AFM transition appears are narrow( and ). We observed a broad maximum of specific heat and magnetic susceptibility. The maximum indicates the existence of AFM and ferromagnetic (FM) short-range order (SRO) at and , respectively. The entropy shows that disordered components of Nd moments generating the FM SRO remain at (the AFM transition temperature) at , similar to the existence of disordered components of Nd moments generating the AFM SRO at at . The main origin of the AFM and FM SROs is AFM and FM interactions in Nd-Nd dimers (), respectively. A discontinuous AFM-to-FM transition in the interaction occurs between and . The coexistence of the AFM and FM interactions due to compositional inhomogeneity of Ge and Ti likely prevents Nd moments from magnetic ordering in the wide range (). We observed the spin-gap excitation of Cr spins at 7.5 meV in inelastic neutron scattering measurements of NdCrGeTiO. The existence of the spin-gap excitation at 1.8 K indicates no magnetic ordering of Cr spins at K.