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We have performed a joint study of magnetization and magnetoresistance in the antiferromagnetic (AFM) semimetal NdSb under pulsed high magnetic field up to 60 T. We show that NdSb displays extremely large magnetoresistance (XMR), reaching values of 1.77×106% at 1.3 K and 60 T without any sign of saturation. The field-dependent magnetization at 4.2 K reveals a field-induced metamagnetic transition from the AFM to the ferromagnetic state around 9 T. During the metamagnetic transition, a steplike reduction of resistance occurs, resembling the giant magnetoresistance (GMR) behavior in metallic multilayers. The investigation of the Shubnikov-de Haas effect in NdSb suggests that a particular orbital texture might contribute to the XMR effect in addition to the perfect electron-hole compensation. [ABSTRACT FROM AUTHOR]

e report a new pressure-induced phase in TaAs with different Weyl fermions than the ambient structure with the aid of theoretical calculations, experimental transport and synchrotron structure investigations up to 53 GPa. We show that TaAs transforms from an ambient I41md phase (t-TaAs) to a high-pressure hexagonal P-6m2(h-TaAs) phase at 14 GPa, along with changes of the electronic state from containing 24 Weyl nodes distributed at two energy levels to possessing 12 Weyl nodes at an isoenergy level, which substantially reduces the interference between the surface and bulk states. The new pressure-induced phase can be reserved upon releasing pressure to ambient condition, which allows one to study the exotic behavior of a single set of Weyl fermions, such as the interplay between surface states and other properties. [ABSTRACT FROM AUTHOR]