Konferenzvorträge

It is known that tiny differences in physical parameters can lead to significant effects, such as symmetry breaking. The small effects observed in the diffraction patterns of bismuth ferrite ($\alpha$-BiFeO$_3$—BFO) are the subject of the present review. [...]

Quantum magnets with geometrical frustration stand out due to their highly degenerate ground states and their susceptibility to be tuned by applying pressure or magnetic field. Such tuning can lead to quantum phase transitions from ordered to disordered states, or vice versa, with the emergent quantum critical points (QCPs) determining the deformed entropy landscapes in the respective phase diagrams. [...]

We present evidence for the presence of a field-induced quantum critical point (QCP) at 21.9(1) T (H || c axis) in the frustrated quantum magnet atacamite Cu$_2$Cl(OH)$_3$, a mineral which we have recently identified as a material realization of sawtooth chains [J ~ 336 K (basal-basal), J' ~ 102 K (basal-apical)]. Residual interchain couplings lead to long-range antiferromagnetic order in atacamite below $T_\mathrm{N}$ = 8.9(1) K. [...]