AP-09: Magnetic fied-induced narrow first-order and metamagnetic phase transitions of Nd5Ge3: Magnetization, muon spin relaxation and neutron diffraction study

We investigate the magnetic nature of a hexagonal structured Nd5Ge3 using magnetization, muon spin relaxation and neutron diffraction measurements. A field dependent thermomagnetic irreversibility distinguishes the magnetic glass (MG) and reentrant spin glass (RSG) states at low temperatures. In zero field, the alloy undergoes a weak first-order magnetic phase transition from antiferromagnetic (AFM) to MG state, which ceases in H>10 kOe. Further, a transition from ferromagnetic (FM) to RSG persists up to about 50 kOe and above which a continuous transition from paramagnetic to FM state is reported. Phase diagram (H-T) identifies two regions; AFM + MG in low fields and FM + RSG states in high fields. The temperature dependent-magnetization, muon depolarization rate (λ), initial asymmetry (A0) and the stretched exponent (β) show a clear anomaly at the Néel temperature and a low-T glassy state. From the neutron diffraction analysis, a field-driven metamagnetic transition (AFM to FM) is confirmed and the magnetic structure of FM state is presented [1-5]. This work was performed at the IIT Bombay and ISIS Neutron and Muon Sources, supported by Newton-India fund (Expt. RB No: 1610200) and DST-India and JNCASR-Bangalore (Expt. RB No: 1768039).References: [1] T. Tsutaoka, A. Tanaka, Y. Narumi, M. Iwaki and K. Kindo, Physica B, 2010, 405, 180 – 185. [2] P. Schobinger-Papamontellos and K. Buschow, J. Magn. Magn. Mater., 1985, 49, 349 – 356. [3] B. Maji, K. G. Suresh and A. K. Nigam, Europhys. Lett., 2010, 91, 37007. [4] B. Maji, K. G. Suresh and A. K. Nigam, J. Phys.: Condens. Matter, 2011, 23, 506002. [5] Samatham et al., Present work (unpublished).