CrFe 2 Ge 2 : Investigation of novel ferromagnetic material of Fe 13 Ge 8 -type crystal structure

We successfully synthesized a novel intermetallic compound CrFe 2 Ge 2 with the Fe 13 Ge 8 -type crystal structure. A structural study is presented combining single-crystal X-ray diffraction and Mössbauer spectroscopy analysis, confirming the presence of two distinct Fe sublattices. CrFe 2 Ge 2 exhibits a metallic ferromagnetic state with T C ≈ 200 K . This material does not follow the usual M 2 ∝ H / M Arrott law, rather a modified Arrott law is obeyed in this material. The critical exponents determined from detailed analysis of modified Arrott plots were found to be β = 0 . 392 , γ = 1 . 309 and δ = 4 . 26 obtained from the critical isotherm at T C = 200 K . Self-consistency and reliability of the critical exponent analysis were verified by the Widom scaling law and scaling equations. Using the results from renormalization group calculation, the critical behavior of CrFe 2 Ge 2 is akin to that of a d = 3 , n = 3 ferromagnet in which the magnetic exchange distance is found to decay as J ( r ) ≈ r − 4 . 86 with long-range magnetic coupling. The evaluated Rhodes–Wohlfarth ratio of ∼ 3 points to an itinerant ferromagnetic ground state. Low-temperature measurements of resistivity, p ( T ) , and specific heat, C P ( T ) , reveal a pronounced contribution from electron–magnon scattering.