In classical (formula presented) kagomé antiferromagnets, there can be a low-temperature phase where (formula presented) has quasi-long-range order but (formula presented) is disordered, as well as more conventional antiferromagnetic phases where (formula presented) is ordered in various possible patterns (formula presented) is the angle of orientation of the spin). To investigate when these phases exist in a physical system, we study superconducting kagomé wire networks in a transverse magnetic field when the magnetic flux through an elementary triangle is a half of a flux quantum. Within Ginzburg-Landau theory, we calculate the helicity moduli of each phase to estimate the Kosterlitz-Thouless (KT) transition temperatures. Then at the KT temperatures, we estimate the barriers to move vortices and the effects that lift the large degeneracy in the possible (formula presented) patterns. The effects we have considered are inductive couplings, nonzero wire width, and the order-by-disorder effect due to thermal fluctuations. The first two effects prefer (formula presented) patterns, while the last one selects a (formula presented) pattern of supercurrents. Using the parameters of recent experiments, we conclude that at the KT temperature, the nonzero wire width effect dominates, which stabilizes a conventional superconducting phase with a (formula presented) current pattern. However, by adjusting the experimental parameters, for example by bending the wires a little, it appears that the (formula presented) superconducting phase can instead be stabilized. The barriers to vortex motion are low enough that the system can equilibrate into this phase.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Jan 1 2001|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics