Abstract
We study the thermodynamics and critical behavior of neutron $^3P_2$ superfluids in the inner cores of neutron stars. $^3P_2$ superfluids offer a rich phase diagram including uniaxial/biaxial nematic phases, the ferromagnetic phase, and the cyclic phase. Using the Bogoliubov-de Gennes (BdG) equation as superfluid Fermi liquid theory, we show that a strong (weak) magnetic field drives the first (second) order transition from the dihedral-two biaxial nematic phase to dihedral-four biaxial nematic phase in low (high) temperatures, and their phase boundaries are divided by the critical endpoint (CEP). We demonstrate that the set of critical exponents at the CEP satisfies the Rushbrooke, Griffiths, and Widom equalities, indicating a new universality class. At the CEP, the $^3P_2$ superfluid exhibits critical behavior with nontrivial critical exponents, indicating a new universality class. Furthermore, we find that the Ginzburg-Landau (GL) equation up to the 8th-order expansion satisfies three equalities and properly captures the physics of the CEP. This implies that the GL theory can provide a tractable way for understanding critical phenomena which may be realized in the dense core of realistic magnetars.
Highlights
A neutron star is a compact star which is composed almost entirely of neutrons under extreme conditions such as high density, rapid rotation, and a strong magnetic field
Using the Bogoliubov–de Gennes equation as in superfluid Fermi liquid theory, we show that a strong magnetic field drives the first-order transition from the dihedraltwo biaxial nematic phase to the dihedral-four biaxial nematic phase at low temperatures and their phase boundaries are divided by the critical end point (CEP)
We show that the phase diagram of 3P2 superfluids under strong magnetic fields has the CEP and compute the critical exponents, indicating a different universality class
Summary
A neutron star is a compact star which is composed almost entirely of neutrons under extreme conditions such as high density, rapid rotation, and a strong magnetic field (see Refs. [1,2] for recent reviews). The other phases are nonunitary states with broken time-reversal symmetry and promising platforms to host Weyl superfluidity [61,62] In addition to such exotic fermions, the 3P2 order parameters bring about rich bosonic excitations [63,64,65,66,67,68,69,70,71,72,73,74,75], which might be relevant to the cooling process by neutrino emission, as well as exotic topological defects, including spontaneously magnetized vortices [27,56,57,59] and vortices with Majorana fermions [77], solitonic excitations on a vortex [78], and half-quantized non-Abelian vortices [60], domain walls [79], and surface topological defects (boojums) on the boundary of 3P2 superfluids [80]. We show that the phase diagram of 3P2 superfluids under strong magnetic fields has the CEP and compute the critical exponents, indicating a different universality class. The set of equations (6)–(9) provides a starting point for deriving the quasiclassical Fermi liquid theory for 3P2 superfluids
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
