BHkurven

BHkurven, or B-H curves, describe the relationship between magnetic flux density B and magnetic field strength H for a material at a given temperature. They are fundamental in magnetism and materials science, illustrating how materials respond to external magnetic fields. The axes typically plot B (in tesla) against H (in ampere-turns per meter). In paramagnetic and many linear ferromagnets at small fields, B grows roughly linearly with H, with slope determined by the material's initial permeability. In ferromagnets, the relation becomes nonlinear and exhibits hysteresis: when H is cycled, the material follows a major hysteresis loop, which closes at a nonzero remanent flux density Br and a nonzero coercive field Hc. The saturation flux density Bs is the plateau reached at large H.

The BH-curve is used to characterize magnetic properties such as Br, Hc, and Bs, as well as to evaluate energy losses (the area inside the loop) during alternating-current cycling. The curve also informs magnetic circuit design, transformers, inductors, electric motors, and magnetic storage technologies. Temperature and material history affect the curve; annealing, mechanical stress, and aging can alter Br, Hc, and Bs.

Measurement methods include loop tracing with a B-H tracer, vibrating-sample magnetometry, and SQUID-based techniques. In practice, BH curves are complemented by minor loops and recoil curves to capture material behavior under varying magnetic histories.