As one of the most promising Kitaev quantum-spin-liquid(QSL)candidates,α-RuCl_(3)has received a great deal of attention.However,its ground state exhibits a long-range zigzag magnetic order,which defies the QSL phase....As one of the most promising Kitaev quantum-spin-liquid(QSL)candidates,α-RuCl_(3)has received a great deal of attention.However,its ground state exhibits a long-range zigzag magnetic order,which defies the QSL phase.Nevertheless,the magnetic order is fragile and can be completely suppressed by applying an external magnetic field.Here,we explore the evolution of magnetic excitations ofα-RuCl;under an in-plane magnetic field,by carrying out inelastic neutron scattering measurements on high-quality single crystals.Under zero field,there exist spin-wave excitations near the M point and a continuum near theΓpoint,which are believed to be associated with the zigzag magnetic order and fractional excitations of the Kitaev QSL state,respectively.By increasing the magnetic field,the spin-wave excitations gradually give way to the continuous excitations.On the verge of the critical fieldμ_(0)H_(c)=7.5 T,the former ones vanish and only the latter ones are left,indicating the emergence of a pure QSL state.By further increasing the field strength,the excitations near theΓpoint become more intense.By following the gap evolution of the excitations near theΓpoint,we are able to establish a phase diagram composed of three interesting phases,including a gapped zigzag order phase at low fields,possibly gapless QSL phase nearμ;H;,and gapped partially polarized phase at high fields.These results demonstrate that an in-plane magnetic field can driveα-RuCl;into a long-sought QSL state near the critical field.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2021YFA1400400)the National Natural Science Foundation of China(Grant Nos.11822405,12074174,12074175,92165205,11904170,12004249,12004251,and 12004191)+1 种基金the Natural Science Foundation of Jiangsu Province(Grant Nos.BK20180006,BK20190436,and BK20200738)the Shanghai Sailing Program(Grant Nos.20YF1430600 and 21YF1429200)。
文摘As one of the most promising Kitaev quantum-spin-liquid(QSL)candidates,α-RuCl_(3)has received a great deal of attention.However,its ground state exhibits a long-range zigzag magnetic order,which defies the QSL phase.Nevertheless,the magnetic order is fragile and can be completely suppressed by applying an external magnetic field.Here,we explore the evolution of magnetic excitations ofα-RuCl;under an in-plane magnetic field,by carrying out inelastic neutron scattering measurements on high-quality single crystals.Under zero field,there exist spin-wave excitations near the M point and a continuum near theΓpoint,which are believed to be associated with the zigzag magnetic order and fractional excitations of the Kitaev QSL state,respectively.By increasing the magnetic field,the spin-wave excitations gradually give way to the continuous excitations.On the verge of the critical fieldμ_(0)H_(c)=7.5 T,the former ones vanish and only the latter ones are left,indicating the emergence of a pure QSL state.By further increasing the field strength,the excitations near theΓpoint become more intense.By following the gap evolution of the excitations near theΓpoint,we are able to establish a phase diagram composed of three interesting phases,including a gapped zigzag order phase at low fields,possibly gapless QSL phase nearμ;H;,and gapped partially polarized phase at high fields.These results demonstrate that an in-plane magnetic field can driveα-RuCl;into a long-sought QSL state near the critical field.
