Cluster spin glass behavior in geometrically frustrated Zn3V3O8
  We report the bulk magnetic properties of a yet unexplored vanadium-based multivalued spinel system, Zn3V3O8. A Curie-Weiss fit of our dc magnetic susceptibility data in the temperature region from 140 to 300 K yields a Curie constant C = 0.75cm3K/mole V, theta CW = -370 K. We have observed a splitting between the zero field cooled ZFC and field cooled FC susceptibility curves below a temperature Tirr of about 6.3 K. The value of the 'frustration parameter' nearly equals to 100 suggests that the system is strongly frustrated. From the ac susceptibility measurements we find a logarithmic variation of freezing temperature (Tf ) with frequency attesting to the formation of a spin glass below Tf . However, the value of the characteristic frequency obtained from the Vogel-Fulcher fit suggests that the ground state is closer to a cluster glass rather than a conventional spin glass. We explored further consequences of the spin glass behavior and observed aging phenomena and memory effect (both in ZFC and FC). We found that a positive temperature cycle erases the memory, as predicted by the hierarchical model. From the heat capacity CP data, a hump-like anomaly was observed in CP /T at about 3.75 K. Below this temperature the magnetic heat capacity shows a nearly linear dependence with T which is consistent with the formation of a spin glass state below Tf in Zn3V3O8. 
Tanmoy Chakrabarty, Avinash V. Mahajan, Susanta Kundu
cond-mat.str-el