We revisit the problem of adsorption of a single^(4)He layer on graphene,focusing on the commensurate(C_(1/3))crystalline phase,specifically on whether it may possess a nonzero superfluid response,and on the existence...We revisit the problem of adsorption of a single^(4)He layer on graphene,focusing on the commensurate(C_(1/3))crystalline phase,specifically on whether it may possess a nonzero superfluid response,and on the existence of superfluid phases,either(metastable)liquid or vacancy-doped crystalline.We make use of canonical quantum Monte Carlo simulations at zero and finite temperature,based on a realistic microscopic model of the system.Our results confirm the absence of any superfluid response in the commensurate crystal,and that no thermodynamically stable uniform phase exists at lower coverage.No evidence of a possibly long-lived,metastable superfluid phase at C_(1/3)coverage is found.Altogether,the results of ground-state projection methods and finite-temperature simulations are entirely consistent.展开更多
We carry out a theoretical investigation of the low-temperature phase diagram of muonium hydride in two dimensions,using numerical simulations.It is shown that the phase diagram of this substance is qualitatively diff...We carry out a theoretical investigation of the low-temperature phase diagram of muonium hydride in two dimensions,using numerical simulations.It is shown that the phase diagram of this substance is qualitatively different in two and three dimensions.Specifically,while in three dimensions it is essentially identical to that of parahydrogen,i.e.,only displaying a single(crystalline)phase.In two dimensions it is very similar to that of^(4)He,with an equilibrium liquid phase that turns superfluid at a temperature as high as~2.2 K,and crystallizes under applied pressure.This is a well-described case of a continuous-space condensed matter system whose ground state equilibrium phase is qualitatively altered by dimensional reduction.展开更多
文摘We revisit the problem of adsorption of a single^(4)He layer on graphene,focusing on the commensurate(C_(1/3))crystalline phase,specifically on whether it may possess a nonzero superfluid response,and on the existence of superfluid phases,either(metastable)liquid or vacancy-doped crystalline.We make use of canonical quantum Monte Carlo simulations at zero and finite temperature,based on a realistic microscopic model of the system.Our results confirm the absence of any superfluid response in the commensurate crystal,and that no thermodynamically stable uniform phase exists at lower coverage.No evidence of a possibly long-lived,metastable superfluid phase at C_(1/3)coverage is found.Altogether,the results of ground-state projection methods and finite-temperature simulations are entirely consistent.
基金supported by the Natural Sciences and Engineering Research Council of Canada,and by the China Scholarship Council。
文摘We carry out a theoretical investigation of the low-temperature phase diagram of muonium hydride in two dimensions,using numerical simulations.It is shown that the phase diagram of this substance is qualitatively different in two and three dimensions.Specifically,while in three dimensions it is essentially identical to that of parahydrogen,i.e.,only displaying a single(crystalline)phase.In two dimensions it is very similar to that of^(4)He,with an equilibrium liquid phase that turns superfluid at a temperature as high as~2.2 K,and crystallizes under applied pressure.This is a well-described case of a continuous-space condensed matter system whose ground state equilibrium phase is qualitatively altered by dimensional reduction.
