Multiple First Order Transitions in Cr Thin Films

RAMIRO HERNÁN RODRIGUEZ; LEANDRO TOSI; MARIELA MENGHINI; HERNAN PASTORIZA; CARLOS A. BALSEIRO

Conferencia; 27th International Conference on Low Temperature Physics (LT27); 2014

The incommensurate spin density wave (SDW) in metalic Cr forms below TN =311K and is characterized by a temperature dependent wave-vector Q along the direction. The wavelength varies from 78A at 300K to 60A at 150 K. In thin lms, the Q-vector orients perpendicular to the lm surface and the SDW is forced to satisfy boundary conditions. As a consequence of the connement, the SDW wavelength is quantized in a set of available modes, each one having n nodes. As the temperature decreases the wavelength does not follow a continuous bulk-type variation but jumps between dierent allowed values. These jumps occur at certain determined temperatures Tn as rst order type transitions which are accompanied with a decrease (n to n + 1 nodes) or an increase (n + 1 to n nodes) of the resistance. In this work, we present transport measurements on Cr thin lms showing hysteretic behavior in the resistance as a function of temperature in cooling-warming cycles. The hysteresis loops are thickness dependent and present structures which we associate with the possible multiple transitions that may occur as temperature is swept.