Magnetic susceptibility of one-dimensional spin chains S(Ni-=SUP=-2+-=/SUP=-)=1 single crystal Y-=SUB=-2-=/SUB=-BaNiO-=SUB=-5-=/SUB=- in the region of 1.85-800 K

Abstract

The magnetic susceptibility of chi(T) one-dimensional spin chains (OSCs) of a single crystal Y2BaNi05 was first studied in the range of 1.85-800 K. In the region from 800 to ~520 the OCC exhibits Curie-Weiss paramagnetism, in which chi0(T)=C/(T+800), where C is the Curie constant, with an effective magnetic moment of μeff=3.75 μB. With a decrease from 520 to 40 K, the susceptibility changes as a Halden magnet with a gap Delta=117 K, chi(T)=chi0(T)exp(-117/T). Below 40 K chi(T) grows again according to the Curie-Weiss law with μeff=3.75μB, thetai1=-3 K and ni1=9.3·1019 spins S(Ni2+)=1 per mole in a crystal grown in an oxygen-free environment; and thetai2=-1.3 K, and ni2=4.6·1019 spins S(Ni2+)=1 after annealing this crystal to 1000oC in air and its subsequent slow cooling.Such a change in the "impurity" contribution to chi(T) of the OCC is presumably due to a lack of O2 in a significant proportion of the terminal spins in the OCC of a single crystal Keywords: energy gap, SQUID measurements in the region of 1.85-800 K, end spins, breaks in the spin chain.