Magnetoresistance of semi metals

Magnetoresistance (MR) is the change in the electrical resistance of a material in the presence of a magnetic field. A large variety of systems display large magnetoresistance and are commonly used in magnetic sensors or memories. Since the pionner works of Kapitza on bismuth it is known that semi metals can display a large magneto resistance. Recently, large magnetoresistance has been reported in a variety of topologically non-trivial band dispersion systems. This has sparked intense debates about its origin. Through the study of the angular dependence of the MR of semi metals (as illistrated on Fig.1) we are aiming to identify the physical parameters which pin down this remarkable large MR. These works are done in close collaboration with Y. Fuseya.

Fig .1: Polar plots of transverse magnetoresistance of bismuth as a function of the orientation of the magnetic field at T=30K and B=0.5 K for three directions of the current injection : j//binary, bissectrix and trigonal