Field-orientation-dependent anisotropic magnetic couplings in multiple magnetic ordering system NdMn2Ge2

Tetragonal NdMn2Ge2, a material exhibiting multiple non-collinear magnetic ordering phases, holds significant application potential. Herein, we systematically investigate the magnetic entropy change of NdMn2Ge2. Critical exponents are determined as β=0.372(1), γ=1.372(6), δ=4.69(4) for H//c, and β=0.436(6), γ=1.508(5), δ=4.46(2) for H//ab. Critical exponents for H//c closely align with the three-dimensional Heisenberg model, indicating isotropic short-range magnetic interactions. In contrast, those for H//ab do not conform to any single theoretical universality class. The distinct anisotropic critical exponents underscore field-orientation-dependent magnetic interactions, crucial for understanding non-collinear spin textures in this system.