Closely linear temperature dependence of exchange bias and coercivity in out-of-plane exchange-biased [Pt/Co] ₃/NiO (11 Å) multilayer

Authors

Z.Y. Liu, University of Nebraska - Lincoln
Shireen Adenwalla, University of Nebraska-LincolnFollow

Date of this Version

July 2003

Comments

Published by American Institute of Physics. J. Applied Physics 93\4, 1105 (2003). ©2003 American Institute of Physics. Permission to use. http://jap.aip.org/jap/.

Abstract

Strong out-of-plane exchange biasing has been observed in out-of-plane exchange biased [Pt (5 Å)/Co (4 Å)] ₃/NiO (11 Å) multilayer with perpendicular easy axis. Both the exchange field H_E and coercivity H_C display a closely linear temperature dependence except at very low temperatures. A thin NiO layer coated on the top of a Pt/Co multilayer has a great effect on the domain pattern of the Pt/Co multilayer, which is in a more irregular configuration with much smaller domain sizes than the uncoupled Pt/Co multilayer. A simulation according to Malozemoff's random field model gives a good agreement to the experimental temperature dependence of H_E and H_E, suggesting that the closely linear temperature dependences of H_E and H_C are strongly related to the behavior of the temperature of anisotropies and of the spin rotation inside the domain walls of a thin NiO layer. The blocking temperature of T_B= 220 K is much higher than that observed in ferromagnetic/thin NiO systems with in-plane anisotropy.