An external magnetic field induces first-order helix-fan phase transition only if the spin-spin turn angle Q is lesser than π/2, while the helix is distorted continously by the field into the saturated paramagnetic phase when Q>π/2. Our calculation is valid for a generic value of the field and our conclusion is in contrast with previous expectations based on low-field-high-field expansion of the zero-temperature energy of the planar model.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics