arXiv subjects

Mark Golden

Publications and source records attributed to Mark Golden.

3 recordsLinked to original sources

arXiv2025

Holographic Strange Metals for Philosophers and Physicists

This paper introduces the physics and philosophy of strange metals, which are characterized by unusual electrical and thermal properties that deviate from conventional metallic behaviour. The anomalous strange-metal behaviour discussed here appears in the normal state of a copper-oxide high-temperature superconductor, and it cannot be described using standard condensed-matter physics. Currently, it can only be described through a holographic dual, viz.~a four-dimensional black hole in anti-de Sitter spacetime. This paper first introduces the theory of, and specific experiments carried out on, strange metals. Then it discusses a number of philosophical questions that strange metals open up regarding the experimental evidence for holography and its realist interpretation. Strange metals invert the explanatory arrows, in that usual holographic arguments are seen as giving explanations of the bulk quantum-gravity theory from the boundary. By contrast, the aim here is, by using holography, to explain the experimentally discovered and anomalous properties of strange metals.

physics.hist-ph↗

arXiv2024

Gauge-gravity duality comes to the lab: evidence of momentum-dependent scaling exponents in the nodal electron self-energy of cuprate strange metals

We show that the momentum-dependent scaling exponents of the holographic fermion self-energy of the conformal-to-AdS$_2$ Gubser-Rocha model can describe new findings from angle-resolved photoemission spectroscopy experiments on a single layer (Pb,Bi)$_{2}$Sr$_{2-x}$La$_x$CuO$_{6+\delta}$ copper-oxide. In particular, it was recently observed, in high-precision measurements on constant energy cuts along the nodal direction, that the spectral function departs from the Lorentzian line shape that is expected from the power-law-liquid model of a nodal self-energy, with an imaginary part featureless in momentum as $\Sigma''_{\text{PLL}}(\omega) \propto (\omega^2)^\alpha$. By direct comparison with experimental results, we provide evidence that this departure from either a Fermi liquid or the power-law liquid, resulting in an asymmetry of the spectral function as a function of momentum around the central peak, is captured at low temperature and all dopings by a semi-holographic model that predicts a momentum-dependent scaling exponent in the electron self-energy as $\Sigma(\omega,k) \propto \omega (-\omega^2)^{\alpha (1 - (k - k_F)/k_F) - 1/2}$, with $\hbar k_F$ the Fermi momentum.

cond-mat.str-el↗

arXiv2016

Direct bulk sensitive probe of 5f symmetry in URu2Si2

The second-order phase transition into a hidden order phase in URu$_2$Si$_2$ goes along with an order parameter which is still a mystery, despite 30 years of research. However, it is understood that the symmetry of the order parameter must be related to the symmetry of the low lying local electronic $f$-states. Here we present results of a novel spectroscopy, namely core-level non-resonant inelastic x-ray scattering (NIXS). This method allows for the measurement of local high-multipole excitations and it is bulk sensitive. The observed anisotropy of the scattering function unambiguously shows that the 5$f$ ground state wave function is composed mainly, but essentially not purely, of the $\Gamma_1$ with majority $J_z$ =$|4\rangle$ + $|-4\rangle$ and/or $\Gamma_2$ singlet states.

cond-mat.str-el↗