Kavli Affiliate: Long Zhang
| First 5 Authors: Yuejiu Zhao, Long Zhang, , ,
| Summary:
Quenched disorders can strongly influence the physical properties of quantum
many-body systems. The real-space strong-disorder renormalization group (SDRG)
analysis has shown that the spin-1/2 random Heisenberg chain is controlled by
the infinite-randomness fixed point (IRFP) and forms a random singlet (RS)
ground state. Motivated by recent thermal transport experiments on the
quasi-one-dimensional antiferromagnet copper benzoate [B. Y. Pan et al, Phys.
Rev. Lett. {bf 129}, 167201 (2022)], we adapt the SDRG to study the
low-temperature properties of the random Heisenberg chain by assuming that its
low-energy excited states are captured by the parent Hamiltonian of the RS
ground state as well. We find that while the specific heat coefficient and the
uniform magnetic susceptibility scale as $C/Tsim T^{-alpha_{c}}$ and
$chisim T^{-alpha_{s}}$ with $0<alpha_{c,s}<1$, indicating a divergent
low-energy density of states, the thermal and the spin conductivities scale as
$kappa/Tsim T$ and $sigma_{s}sim T$, which implies a vanishing density of
extended states in the low-energy limit. We believe that such a disparity in
the thermodynamic and transport properties is a common feature of random
systems controlled by the IRFP.
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