Hyperfine Interact (2008) 184:155–159 DOI 10.1007/s10751-008-9782-x Magnetism of (Fe 0.93 Ni 0.07 ) 2 P studied using 57 Fe Mössbauer spectroscopy Sudhish Kumar · Anjali Krishnamurthy · Bipin K. Srivastava Published online: 7 October 2008 © Springer Science + Business Media B.V. 2008 Abstract 57 Fe Mössbauer spectroscopic measurements have been carried out on (Fe 0.93 Ni 0.07 ) 2 P in the temperature range 85–405 K. Obtained values of hyperfine field at the two metallic sites are slightly smaller than in Fe 2 P. But the reduction is much less than as reported in Cr or Mn or Co substituted analogues of Fe 2 P. Keywords Fe 2 P · Magnetism · Magnetic interactions · Mössbauer spectroscopy 1 Introduction Recently, magneto-caloric effect, magneto-elastic properties, neutron diffraction studies and electronic structures have been reported for alloys in the series (Fe 1−x Ni x ) 2 P[1–3]. It has been shown that low level Ni substituted compounds exhibit first order ferromagnetic to paramagnetic phase transition. Strong electron polarization at E F is responsible for the magneto-elastic phase transitions in the compound with small substitution of Ni. Magnetic properties of these compounds are quite similar to those of the magneto-caloric materials like MnFeP 1−y As y [4]. In our recent study on (Fe 0.93 Ni 0.07 ) 2 P, we have shown that this compound undergoes field induced type first order magnetic phase transition at ∼298 K. There is no crystallographic structural transition associated with the magnetic phase tran- sition. The transition is caused by a change in the c/a ratio. The alloy retains ferromagnetic order of Fe 2 P with the moments orienting along [001] direction. Ratio of paramagnetic moment to saturation moment (μ p /μ s ) in this alloy is 1.53 (>1), which as per Rhodes–Wohlfarth criterion is suggestive of itinerant magnetism. At S. Kumar (B ) Department of Physics, M.L. Sukhadia University, Udaipur 313 002, India e-mail: skmlsu@gmail.com A. Krishnamurthy · B. K. Srivastava Department of Physics, University of Rajasthan, Jaipur 302 004, India