Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Pressure-induced phase switching of the Shubnikov de Haas oscillations
  in molecular Dirac fermion system $\alpha-$(BETS)$_{2}$I$_{3}$   We report on the Shubnikov de Haas (SdH) oscillations in the quasi
two-dimensional molecular conductor $\alpha-$(BETS)$_{2}$I$_{3}$ [BETS:
bis(ethylenedithio)tetraselenafulvalene] laminated on polyimide films at 1.7 K.
From the SdH phase factor, we verified experimentally that the material is in
the Dirac fermion phase under pressure. $\alpha-$(BETS)$_{2}$I$_{3}$ is in the
vicinity of the phase transition between strongly correlated insulating and
Dirac fermion phases, and is a possible candidate for an ambient-pressure
molecular Dirac fermion system. However, the SdH oscillations indicate that the
Berry phase is zero at ambient pressure. Under pressure, a $\pi$ Berry phase
emerges when the metal-insulator crossover is almost suppressed at $\sim$0.5
GPa. The results contrast those for the pioneering molecular Dirac fermion
system $\alpha-$(BEDT-TTF)$_{2}$I$_{3}$ [BEDT-TTF:
bis(ethylenedithio)tetrathiafulvalene] in which Dirac fermions and
semiconducting behavior are simultaneously observed.

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The categories of this paper are: astro-ph
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The categories of this paper are: cs
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: math
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The categories of this paper are: atom-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: adap-org
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The categories of this paper are: econ
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The categories of this paper are: eess
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: q-bio
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The categories of this paper are: alg-geom