Anomalous electrical transport behavior in the vicinity of the first-order magnetostructural transition in the giant magnetocaloric Gd4ScGe4

Magnetic, specific heat, and electrical transport measurements of Gd4ScGe4 single crystals reveal sharp, discontinuous, nearly anhysteretic first-order magnetostructural transformation at T-C = 63 K. The electrical resistivity exhibits two distinct regions where it increases with decreasing temperature: between T-C and 120 K, as well as below 3 K; electronic transport remains conventionally metallic at all other measured temperatures, up to 325 K. The dispersion of charge carriers due to electron-paramagnon scattering is the likely reason for the observed anomalous transport above T-C. Additionally, the existence of intermediate lattice states near the transition recognized by the spike in the interslab Ge-Ge distances is expected to reduce the mean free path of the electrons contributing to the unusual behavior of the electrical resistivity between T-C and 120 K. Beyond conventional electronic and lattice terms, the third component of likely magnetic origin contributes to the low-temperature heat capacity; the presence of spin waves may be responsible for the increased electron-magnon scattering below 3 K. Minor magnetocrystalline anisotropy is observed with the b axis as the easy magnetization axis in Gd4ScGe4. A negative deviation from linearity in the temperature dependence of the inverse magnetic susceptibility is detected below 150 K.

Automated summary

Magnetic, specific heat, and electrical transport measurements of Gd4ScGe4 single crystals reveal a sharp magnetostructural transformation at 63 K. The electrical resistivity shows anomalous behavior due to electron-paramagnon scattering and intermediate lattice states. The low-temperature heat capacity is influenced by a magnetic component and electron-magnon scattering caused by spin waves.