Suppression of Biquadratic Coupling in Fe<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mo>/</mml:mo></mml:math>Cr(001) Superlattices below the Néel Transition of Cr

Abstract

The N\'eel temperature ( ${T}_{N}$) of Cr in sputtered, epitaxial Fe $/$Cr(001) superlattices is identified via transport and magnetic anomalies. The onset of the antiferromagnetism is at a thickness ${t}_{\mathrm{Cr}}$ of 42 \AA{}. The bulk value of ${T}_{N}$ is approached asymptotically as ${t}_{\mathrm{Cr}}$ increases and is characterized by a three-dimensional shift exponent. Most strikingly, the biquadratic interlayer magnetic coupling (90\ifmmode^\circ\else\textdegree\fi{} orientation of adjacent Fe layers), observed in the thick Cr regime, is suppressed below ${T}_{N}$. These results are attributed to finite-size effects and spin frustration near rough Fe-Cr interfaces.