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Scientists Reveal Planar Hall Effect in Dirac Semimetal Nanoplates

Dec 26, 2018

Scientists in High Magnetic Field Laboratory, Chinese Academy of Sciences (CAS), reported new results in probing the chiral anomaly by planar Hall effect in Dirac semimetal Cd3As2 nanoplates.

Due to the potential impact on information technology, topological semimetals have inspired intense interests. One of the most exotic properties intopological semimetals is the chiral anomaly.

Experimentally, the observed negative longitudinal magnetoresistivity was usually labeled as the signature of chiral anomaly and had been observed in Dirac semimetals Na3Bi, Cd3As2, ZrTe5 and GdPtBi, and Weyl semimetals TaAs family.

While the negative longitudinal magnetoresistivity can actually be induced by the axial anomaly due to neutral and ionic impurities, the "current jetting" effect, as well as conductivity fluctuations. Thus, negative longitudinal magnetoresistivity itself becomes an ambiguous transport evidence for the chiral anomaly.

Recent theories indicate that the nontrivial Berry curvature and chiral anomaly can induce another key effect: the Planar Hall Effect, and the Planar Hall Effect, combined with negative longitudinal magnetoresistivity in non-magnetic Weyl semimetals, may provide a key transport signature of the chiral anomaly.

WU Min, a member of TIAN Mingliang's group, carried out the planar Hall measurements on Cd3As2 nanoplates.

He found that accompanied by the large negative longitudinal magnetoresistivity, the Planar Hall effect can be observed while tilting the in-plane magnetic field away from the electric field consecutively.

Further experiments revealed that both the Planar Hall effect and the negative longitudinal magnetoresistivity could be suppressed synchronously with increasing the temperature, but still visible at room temperature, indicating the same origin of these two effects.

Moreover, the amplitudes of the PHE showed -dependence in weak magnetic field limit and -dependence at the quantum limit, respectively.

These results indicated that PHE may provide another key transport evidence for topologically nontrivial electronic structures in topological materials.

The results entitled "Probing the chiral anomaly by planar Hall effect in Dirac semimetal Cd3As2 nanoplates" was published on Physical Review B.

The work is supported by National Natural Science foundation of China.

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