Nonequilibrium quasistationary spin disordered state in α−RuCl3

Abstract

We photoexcite high-energy holon-doublon pairs as a way to alter the magnetic free energy landscape and resulting phase diagram of the frustrated honeycomb magnet α-RuCl 3 . The pair recombination through multimagnon emission is tracked through the time evolution of the magnetooptical response originating from α-RuCl 3 's competing zigzag spin-ordered ground state. A small holon-doublon density suffices to reach a spin-disordered state. The phase transition is described within a dynamical Ginzburg-Landau framework, corroborating the quasistationary nature of the transient phase. Our work suggests a new route to reach a nontrivial spin-disordered state in Kitaev-like magnets.

Ultrafast Spin Dynamics and Photoinduced Insulator-to-Metal Transition in α-RuCl3

“…As the energy of the pump laser surpasses the transient bandgaps, the trends and time scales governing laser-induced magnetic dynamics exhibit comparable behavior and minimal discrepancies for both above- and below-gap excitations. In experiments, the magnetic transition could be probed by the time-resolved linear magnetic dichroism and X-ray magnetic circular dichroism, , which is able to illustrate the magnetic difference. Photoinduced insulator-to-metal transition in α-RuCl 3 can be detected by time- and angle-resolved photoemission spectroscopy.…”

“…Photoinduced demagnetization of magnetic insulators paves the way for launching ultrafast dynamics of spins, which cannot be reached in terms of conventional methods to modulate the microscopic magnetism. ,, Owing to the simple honeycomb crystal structure, the ruthenium-based compound α-RuCl 3 provides an attractive platform to explore the physics of electronic correlations, unconventional magnetism, and optomagnetic effects in correlated insulators. − It is illustrated that α-RuCl 3 accommodates essential ingredients of the Kitaev model owing to the interplay of electron correlations and magnetic interactions, facilitating a variety of exotic quantum phases. − …”

Polar magnetism and chemical bond in α-RuCl3

“…electric dipole-electric dipole (E1-E1) or electric dipole-magnetic dipole (E1-M1) absorption events [23][24][25][26], and not the primary magnetic order-parameter utilized by the authors to interpret their data. Specifically, the assertion in [22] that the data reported in figure 2(b) establishes polarization spectroscopy as an all-optical alternative to magnetic neutron diffraction for probing a zigzag magnetic ground state is not justified.…”

“…As for optical responses, polarization rotation and dichroic signals are prohibited in C c 2/m. These restrictions are violated in optical measurements on a shiny as-grown α-RuCl 3 sample [22]. Data for optical polarization rotation, also referred to by the authors as an equilibrium magneto-optical response or magnetic linear dichroism, are displayed in figure 2(b) of Versteeg et al [22].…”

“…These restrictions are violated in optical measurements on a shiny as-grown α-RuCl 3 sample [22]. Data for optical polarization rotation, also referred to by the authors as an equilibrium magneto-optical response or magnetic linear dichroism, are displayed in figure 2(b) of Versteeg et al [22]. They are used to imply a phase transition in the sample at a temperature around 7 K. Linear dichroism is generated by electronic quadrupoles, be it axial or polar (nonreciprocal dichroism), e.g.…”