The generation of high-order harmonics in gases enabled to probe the attosecond electron dynamics in atoms and molecules with unprecedented resolution.Extending these techniques to solids,which were originally develop...The generation of high-order harmonics in gases enabled to probe the attosecond electron dynamics in atoms and molecules with unprecedented resolution.Extending these techniques to solids,which were originally developed for atomic and molecular gases,requires a fundamental understanding of the physics that has been partially addressed theoretically.Here,we employ timedependent density-functional theory to investigate how the electron dynamics resulting in high-harmonic emission in monolayer hexagonal boron nitride is affected by the presence of vacancies.We show how these realistic spin-polarised defects modify the harmonic emission and demonstrate that important differences exist between harmonics from a pristine solid and a defected solid.In particular,we found that the different spin channels are affected differently by the presence of the spin-polarised point defect.Moreover,the localisation of the wavefunction,the geometry of the defect,and the electron–electron interaction are all crucial ingredients to describe high-harmonic generation in defected solids.展开更多
Time-resolved mapping of lattice dynamics in real-and momentum-space is essential to better understand several ubiquitous phenomena such as heat transport,displacive phase transition,thermal conductivity,and many more...Time-resolved mapping of lattice dynamics in real-and momentum-space is essential to better understand several ubiquitous phenomena such as heat transport,displacive phase transition,thermal conductivity,and many more.In this regard,time-resolved diffraction and microscopy methods are employed to image the induced lattice dynamics within a pump–probe configuration.In this work,we demonstrate that inelastic scattering methods,with the aid of theoretical simulation,are competent to provide similar information as one could obtain from the time-resolved diffraction and imaging measurements.To illustrate the robustness of the proposed method,our simulated result of lattice dynamics in germanium is in excellent agreement with the time-resolved x-ray diffuse scattering measurement performed using x-ray free-electron laser.For a given inelastic scattering data in energy and momentum space,the proposed method is useful to image in-situ lattice dynamics under different environmental conditions of temperature,pressure,and magnetic field.Moreover,the technique will profoundly impact where time-resolved diffraction within the pump–probe setup is not feasible,for instance,in inelastic neutron scattering.展开更多
基金This work was supported by the European Research Council(ERC-2015-AdG694097)the Cluster of Excellence(AIM),Grupos Consolidados(IT1249-19)SFB925,the Flatiron Institute(a division of the Simons Foundation),and Ramanujan fellowship(SB/S2/RJN-152/2015).
文摘The generation of high-order harmonics in gases enabled to probe the attosecond electron dynamics in atoms and molecules with unprecedented resolution.Extending these techniques to solids,which were originally developed for atomic and molecular gases,requires a fundamental understanding of the physics that has been partially addressed theoretically.Here,we employ timedependent density-functional theory to investigate how the electron dynamics resulting in high-harmonic emission in monolayer hexagonal boron nitride is affected by the presence of vacancies.We show how these realistic spin-polarised defects modify the harmonic emission and demonstrate that important differences exist between harmonics from a pristine solid and a defected solid.In particular,we found that the different spin channels are affected differently by the presence of the spin-polarised point defect.Moreover,the localisation of the wavefunction,the geometry of the defect,and the electron–electron interaction are all crucial ingredients to describe high-harmonic generation in defected solids.
基金G.D.acknowledges fruitful discussion with Sucharita Giri.A.P.R acknowledges the financial support from IRCC-IITB.D.B.thanks the financial support from MHRD-STARS under project no.:STARS/APR2019/PS/345/FSBRNS-DAE under project no.:58/14/30/2019-BRNS/11117+1 种基金G D.acknowledges support from Science and Engineering Research Board(SERB)India(Project No.ECR/2017/001460)the Ramanujan fellowship(SB/S2/RJN-152/2015).
文摘Time-resolved mapping of lattice dynamics in real-and momentum-space is essential to better understand several ubiquitous phenomena such as heat transport,displacive phase transition,thermal conductivity,and many more.In this regard,time-resolved diffraction and microscopy methods are employed to image the induced lattice dynamics within a pump–probe configuration.In this work,we demonstrate that inelastic scattering methods,with the aid of theoretical simulation,are competent to provide similar information as one could obtain from the time-resolved diffraction and imaging measurements.To illustrate the robustness of the proposed method,our simulated result of lattice dynamics in germanium is in excellent agreement with the time-resolved x-ray diffuse scattering measurement performed using x-ray free-electron laser.For a given inelastic scattering data in energy and momentum space,the proposed method is useful to image in-situ lattice dynamics under different environmental conditions of temperature,pressure,and magnetic field.Moreover,the technique will profoundly impact where time-resolved diffraction within the pump–probe setup is not feasible,for instance,in inelastic neutron scattering.
