Professor Zhang’s Group Publishes Paper in Nature

Professor Zhang Xiaozhong of Department of Materials Science and Engineering, Tsinghua University and his PhD student Wan Caihua published their paper entitled “Geometrical enhancement of low-field magnetoresistance in silicon” in Nature on September 15, 2011. Zhang and Wan are the corresponding and first authors, respectively.  This research work is completed independently by Professor Zhang’s group. This is the first time that a Chinese institution as the first working institution publishes their research results in Nature/Science in the field of magnetoresistance.

Inhomogeneity-induced magnetoresistance (IMR) reported in some non-magnetic semiconductors, particularly silicon, has triggered considerable interest owing to the large magnitude of the effect and its linear field dependence. Theories of this effect implicate spatial variation of the carrier mobility as being responsible for IMR. Prof. Zhang’ group show that IMR in lightly doped n-type silicon can be significantly enhanced through hole injection, and then tuned by an applied current to arise at low magnetic fields. They designed an IMR device. In their devices, the 'inhomogeneity' is provided by the p-n boundary formed between regions where conduction is dominated by the holes and electrons respectively; application of a magnetic field distorts the current in the boundary region, resulting in large IMR. This IMR device has a room-temperature magnetoresistance reaching 10% at 0.07 T and 100% at 0.2 T, approaching the performance of commercial giant menetoreistance devices which is widely used in nowadays computer industry. This silicon based IMR device can work both in low and high magnetic fields and this make it attractive to the magnetic field sensing industry. Moreover, because this device is based on a conventional silicon platform, it should be possible to integrate it with existing silicon devices and so aid the development of silicon-based magnetoelectronics.