Emergence of complex magnetic states in Tb₂Zn₁₇ driven by high magnetic fields

We have investigated the magnetic properties of Tb₂Zn₁₇ as a function of temperature and magnetic field (0-14 T). Upon cooling, the system undergoes long range anti-ferromagnetic ordering at T_N1= 21 K, followed by successive spin reorientation phase transitions (SRPTs) at T_N2 = 8 K and T_N3= 2. 43 K. Heat capacity measurements under applied fields of 2, 4, 8, and 14 T reveal the evolution of multiple magnetic phases. To further explore the nature of various SRPTs, detailed dc and ac susceptibility measurements under field cooled cooling (FCC) and field cooled warming (FCW) conditions have been performed. Repeated FCC and FCW dc and ac magnetic susceptibility clearly distinguish a temperature point that separates the continuous and the discontinuous part of the SRPT. A subtle but distinct hysteresis is observed in both the ac and dc magnetic susceptibility measurements, consistent with the heat capacity data recorded during cooling and warming in zero field. The complete reversibility of dc and ac susceptibility data near T_N1 and T_N3 confirms the second order nature of these transitions whereas the transition at T_N2 is first order.