  The Landau Fermi liquid theory, a cornerstone in condensed matter physics,
encounters limitations in explaining certain phenomena, like the peculiar
behavior of strange metals in high-temperature superconductors. Non-Fermi
liquids, like Bose metals with uncondensed bosonic ground state, offer
potential explanations, yet constructing an elusive Bose metal phase in two
dimensions (2D) remains a formidable challenge. Utilizing constraint path
quantum Monte Carlo and functional renormalization group methods on a fermionic
system with spin anisotropy in a 2D lattice, we reveal the emergence of a
Cooper pair Bose metal in a highly anisotropic regime (a < 0.30) with wide
range of filling, most notably at a filling fraction of n~0.8. Our findings
exhibit a visible nonzero momentum Bose surface in the Cooper-pair distribution
function, accompanied by a distinct signal of dxy correlation between pairs.
Our results highlight that spin-dependent anisotropy in the Fermi surface leads
to versatile pairing forms. Platforms such as ultracold atoms in optical
lattices and recently proposed altermagnets hold promise for realizing this
intriguing phase.
