Magnetic and Electrical Transport Properties of NdB₂C₂

We have studied the structural, magnetic, and electrical transport properties of the polycrystalline NdB2C2 material prepared by arc melting and subsequent annealing. It has a tetragonal crystal structure with space group P4/mbm. The lattice parameters were found to be <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$a = b = 5.3561$ </tex-math></inline-formula> Å and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$c = 3.8080$ </tex-math></inline-formula> Å. The sample showed significant texturing/preferred orientation. The magnetization measurements on the polycrystalline sample reveal its paramagnetic nature at room temperature and the antiferromagnetic ordering of the Nd moments near 9 K. The magnetic moment due to rare-earth element Nd obtained from the Curie-Weiss analysis of the thermomagnetic curve has been found to be <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.7~\mu _{\text {B}}$ </tex-math></inline-formula>/f.u., with a negative Curie-Weiss temperature of −40 K. The isothermal magnetization curve measured at 2 K is linear near <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$H = 0$ </tex-math></inline-formula> but shows a signature of field-dependent transitions at higher fields. The resistivity versus temperature measurements corroborate the antiferromagnetic transition observed in the magnetization data and also reveal the metallic nature of the material. Additionally, the Hall effect measurements performed below the Néel temperature reveal an anomalous contribution, which may be associated with the altermagnetism proposed in this material.