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Inconceivably large changes (up to 10 6 %) of the resistivity induced by external magnetic field-a phenomenon known as the extreme magnetoresistance effect has been reported in a great number of exotic semimetals. The very recent and exciting discoveries mainly pay attention to the compounds without magnetic ground states, which appears to limit the potential growth of semimetal family. For fundamental scientific interests, introduction of spin degree of freedom would provide an almost ideal platform for investigating the correlation effect between magnetism, crystallographic structure and electric resistivity in materials. Here, we report the experimental observation of metamagnetic behaviors and transport properties of HoBi single crystals. Being a magnetic member of the rare earth monopnictide family, the magnetoresistance of HoBi is significantly modulated by the magnetic orders at low temperature, which shows a nonmonotonic increment across the successive magnetic phases and reaches 10 4 % (9 T and 2 K) in the ferromagnetic state. Kohler's rule predicts that more than one type of carriers dominates the transport properties. Well fitted magnetoresistance and Hall resistivity curves by the semiclassical two-band model suggest that the densities of electron and hole carriers are nearly compensated and the carrier mobilities in this compound are ultrahigh. Besides, the inverted band structures and nonzero Z 2 topological invariant indicate that possible nontrivial electronic states could generate in the ferromagnetic phase of HoBi. Combining the experimental and theoretical results, it is found that the cooperative action of carrier compensation effect and ultrahigh mobility might contribute to the extreme magnetoresistance observed in the titled compound. These findings suggest a paradigm for obtaining the extreme magnetoresistance in magnetic compounds and are relevant to understand the rare-earth-based correlated topological materials. tunnel magnetoresistance [2-5], extremely large magnetoresistance have attracted increasing interest [6, 7], since it not only offer the potential to design new devices, but also pose challenges to understand the fundamental phenomena in nature. The extreme magnetoresistance has been widely reported in the classic elemental semimetal Bi, topological semimetals WTe 2 , Cd 3 As 2 , TaPn (Pn = As, Sb) family, pyrite-type PtBi 2 , RPtBi (R=Nd, Gd), RPn (R=rare earth; Pn = Sb, Bi) and so on . Ever since the unprecedentedly large magnetoresistance is revealed in LaSb, the research enthusiasm on rare earth monopnictides RPn (R=rare earth, Pn = Sb, Bi) is inspired [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. The family has been widely studied in the 1980-90s for its heavy-fermion nature [31]. Intriguingly, the recent calculations predict that LaPn (Pn = N, P, As, Sb, and Bi) could be a topological prototype material with band inversion at X point of the bulk fcc Brillouin zone [32]. Afterwards, further investigation on this family has been systematically performe...

Anisotropic and extreme magnetoresistance in the magnetic semimetal Anisotropic and extreme magnetoresistance in the magnetic semimetal candidate erbium monobismuthide candidate erbium monobismuthide L Fan F Tang

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The RRS1 regulator of ribosome synthesis has recently been reported a new target gene linked to cancer development. This study therefore investigates RRS1effectsb on BT549 cell proliferation and apoptosis in breast cancer. Western blot (WB) and real-time quantitative PCR (qPCR) were used to detect the relative expression of RRS1 in breast cancer cells BT-549 and the normal HMEC mammary gland epithelial cells. BT-549 cells were cultured and infected with retroviruses and RRS1 expression was detected by qPCR and WB. The MTT assay, Caspase-3/7 and flow cytometry (FCM) then detected growth and apoptosis in the BT549 breast cancer BT cell. WB detected the expression of Bcl-2 and Bax genes related to apoptosis at the protein level, and MTT assay confirmed that RRS1 knockdown significantly decreased cell viability (p<0.05) and induced apoptosis which was rescued by shRNA-RRS1 expression. The amount of caspase-3 increased significantly and apoptosis was obvious. The apoptotic cells amount analyzed by FCM was significantly increased and RRS1 knockdown also decreased the expression of apoptosis related protein bcl-2 and simultaneously increased the expression of Bax (p<0.05). Finally, the RRS1 gene was highly expressed in breast cancer cell line BT549 and its knockdown significantly reduced proliferation and apoptosis in BT549 cell. These results suggest that RRS1 is a novel gene related to breast cancer and has an important role in breast cancer proliferation and apoptosis.