Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High-Field Superconductivity at an Electronic Topological Transition in
  URhGe   The emergence of superconductivity at high magnetic fields in URhGe is
regarded as a paradigm for new state formation approaching a quantum critical
point. Until now, a divergence of the quasiparticle mass at the metamagnetic
transition was considered essential for superconductivity to survive at
magnetic fields above 30 tesla. Here we report the observation of quantum
oscillations in URhGe revealing a tiny pocket of heavy quasiparticles that
shrinks continuously with increasing magnetic field, and finally disappears at
a topological Fermi surface transition close to or at the metamagnetic field.
The quasiparticle mass decreases and remains finite, implying that the Fermi
velocity vanishes due to the collapse of the Fermi wavevector. This offers a
novel explanation for the re-emergence of superconductivity at extreme magnetic
fields and makes URhGe the first proven example of a material where magnetic
field-tuning of the Fermi surface, rather than quantum criticality alone,
governs quantum phase formation.

20
The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
18
The categories of this paper are: econ
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat