Physics Chat
Using high frequency AC susceptibility to probe the low field dynamics of Ca3Co2O6.
Speaker: Clara Cafolla-Ward (SGiblin)
Date: Friday 10 December 2021
Time: 15:00
Venue: Zoom
The geometrically frustrated magnet Ca_3Co2O6 has an interesting magnetic structure that leads to a complex magnetic response with timescales that are highly dependent on temperature and magnetic field history. Many experiments utilising specific heat, magnetisation, neutron diffraction and AC susceptibility have been used to understand the behaviour of this material. Our group has developed a high frequency AC susceptometer that increases the frequency window from 10kHz to 3MHz, allowing greater insight into the development of this material's magnetic and temperature response. Between 10K and 25K, the material's behaviour is dominated by the ferromagnetic and antiferromagnetic interactions between the Ising-like magnetic ions and the effects of hysteresis are small. For these temperatures, the static magnetisation as a function of positive magnetic field has two well defined plateaus, one at a third magnetisation and one at full magnetisation. Between these plateaus are regions of sharp gradient change or transitions that indicates a symmetry breaking. At zero field, the centre of the transition between a third magnetisation and negative a third magnetisation, our AC susceptibility measurements indicate two distinct relaxations times for temperatures between 13K and 23K. The appearance of these two peaks also disappear with increasing magnetic field which could correlate with gradient changes of the magnetisation.
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