Finite size effects in nanoscale Tb particles

Tb nanoscale particles are prepared in a matrix of Ti by sputtering. A range of samples are made with average particle diameter ranging from 1.5 to 21 nm. The magnetic transition temperature is depressed for smaller particles due to finite size effects. The coercivity at 4.5 K shows a maximum of 22 kOe at approximately 7 nm being a factor of 2.4 larger than a thick film of Tb. We compare the coercivity of our particle samples to multilayers of the form Tb/Mo and find larger coercivity in the particle systems due to the more confined geometry of the particles.