Magnetic Order Driven Ultrafast Phase Transition in NdNiO$_3$
V. Stoica, D. Puggioni, J. Zhang, R. Singla, G. L. Dakovski, G. Coslovich, M. H. Seaberg, M. Kareev, S. Middey, P. Kissin, R. D. Averitt, J. Chakhalian, H. Wen,… 展开作者
V. Stoica, D. Puggioni, J. Zhang, R. Singla, G. L. Dakovski, G. Coslovich, M. H. Seaberg, M. Kareev, S. Middey, P. Kissin, R. D. Averitt, J. Chakhalian, H. Wen, J. M. Rondinelli, J. W. Freeland
备注：
9 pages, 5 figures, major revision and title change from previous version
Ultrashort x-ray pulses can be used to disentangle magnetic and structural dynamics and are accordingly utilized here to study the photoexcitation of NdNiO$_3$ (NNO), a model nickelate exhibiting structural and magnetic dynamics that conspire to induce an IMT. During the course of the photoinduced insulator to metal transition (IMT) with above gap excitation, we observe an ultrafast ($<$ 180 fs) quenching of magnetic order followed by a time delayed collapse of the insulating phase probed by X-ray absorption and THz transmission (~ 450 fs) that correlates with the slowest optical phonon mode involved in the structural transition. A simultaneous order-disorder response at the Ni site and displacive response at the Nd site coexist in the ultrafast magnetic response. Crucially, we observe the optical phonon through its coherent coupling with Nd magnetic order, demonstrating that the magnetic and structural degrees of freedom both contribute in driving the IMT. Density functional theory (DFT) calculations reveal a consistent scenario where optically driven inter-site charge transfer (ICT) drives a collapse of antiferromagnetic order that in turn destabilizes the charge-ordered phase resulting in an IMT. These experiments provide new modalities for control of electronic phase transitions in quantum materials based on ultrafast interplay between structural and magnetic orders created by femtosecond photoexcitation.
We use resonant soft X-ray diffraction to track the photo-induced dynamics of the antiferromagnetic structure in a NdNiO$_{3}$ thin film. Femtosecond laser pulses with a photon energy of 0.61 eV, resonant with electron transfer between long-bond and short-bond nickel sites, are used to excite the material and drive an ultrafast insulator-metal transition. Polarization sensitive soft X-ray diffraction, resonant to the nickel L$_{3}$-edge, then probes the evolution of the underlying magnetic spiral as a function of time delay with 80 picosecond time resolution. By modelling the azimuthal depende…
We observed that close to a Mott transition, over a small temperature range, the predominance of slow relaxations leads to decoupling of electrons from the thermal bath. This has been established by observation of large deviation of the thermal noise in the films of Mott system $NdNiO_{3}$ from the canonical Johnson-Nyquist value of $4k_{B}TR$ close to the transition. It is suggested that such a large noise arise from small isolated pockets of nanometric metallic phases (estimated size $\sim$ 15-20 nm) within the insulating phase with the charging energy as the control parameter.
The general idea of using ultrashort light pulses to control ferroic order parameters has recently attracted attention as a means to achieve control over material properties on unprecedented time scales. Much of the challenge in such work is in understanding the mechanisms by which this control can be achieved, and in particular how observables can be connected to structural and electronic properties. Here we report on a combination of experimental and computational methods to study the electronic structure of the semiconducting ferroelectric GeTe when driven out of equilibrium by absorption o…
Nonlinear phononics holds the promise for controlling properties of quantum materials on the ultrashort timescale. Using nonequilibrium dynamical mean-field theory, we solve a model for the description of organic solids, where correlated electrons couple nonlinearly to a quantum phonon mode. Unlike previous works, we exactly diagonalize the local phonon mode within the noncrossing approximation to include the full phononic fluctuations. By exciting the local phonon in a broad range of frequencies near resonance with an ultrashort pulse, we show it is possible to induce a Mott insulator-to-meta…
The nearly free electron metal next to a localized Mott insulating state has been recently proposed as a way to probe Kondo lattice physics and to gain insight into how the two extremes of localized and delocalized electron states interact (Sunko, et al, Science advances 6, 2020). Although high harmonic generation has been used extensively to investigate the gas phase, its extension to solids is relatively recent, and has not yet been applied to interfaces. Here, we investigate the field-induced dielectric break-down at the Mott-insulator/metal interface using high harmonic generation, emitted…
Unveiling High-Energy Ultrafast Responses Driven by Fermi-Level Gap Opening in Charge-Density Waves
Chongqing University（重庆大学）；Peking University（北京大学）；Chongqing University of Arts and Sciences（重庆文理学院）；Max Planck Institute for Chemical Physics of Solids（马克斯·普朗克固体化学物理研究所）；Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area（粤港澳大湾区量子科学中心）；Center for High Pressure Science and Technology Advanced Research（高压科学与技术前沿研究中心）；Beijing Academy of Quantum Information Sciences（北京量子信息科学研究院）；Tsung-Dao Lee Institute, School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院镛沙杜利研究所）
Ultrafast electron crystallography reveals the atomic pathway of a light-driven correlated insulator-to-metal transition
Stockholm University（斯德哥尔摩大学）；Uppsala University（乌普萨拉大学）；Technion–Israel Institute of Technology（以色列理工学院）；KTH Royal Institute of Technology（瑞典皇家理工学院）；Australian National University（澳大利亚国立大学）
We use femtosecond electron diffraction to study ultrafast lattice dynamics in the highly correlated antiferromagnetic (AF) semiconductor NiO. Using the scattering vector (Q) dependence of Bragg diffraction, we introduce a Q-resolved effective lattice temperature, and identify a nonthermal lattice state with preferential displacement of O compared to Ni ions, which occurs within ~0.3 ps and persists for 25 ps. We associate this with transient changes to the AF exchange striction-induced lattice distortion, supported by the observation of a transient Q-asymmetry of Friedel pairs. Our observatio…
Understanding spin-lattice coupling represents a key challenge in modern condensed matter physics, with crucial importance and implications for ultrafast and 2D-magnetism. The efficiency of angular momentum and energy transfer between spins and the lattice imposes fundamental speed limits on the ability to control spins in spintronics, magnonics and magnetic data storage. We report on an efficient nonlinear mechanism of spin-lattice coupling driven by THz light pulses. A nearly single-cycle THz pulse resonantly interacts with a coherent magnonic state in the antiferromagnet CoF2 and excites th…
Nonclassical dynamics of Néel vector and magnetization accompanied by THz and high-harmonic radiation from ultrafast-light-driven NiO antiferromagnet insulator
In a honeycomb-lattice spin-orbit assisted Mott insulator α-RuCl3, an ultrafast magnetization is induced by circularly polarized excitation below the Mott gap. Photo-carriers play an important role, which are generated by turning down the synergy of the on-site Coulomb interaction and the spin-orbit interaction realizing the insulator state. An ultrafast 6- fs measurement of photo-carrier dynamics and a quantum mechanical analysis clarify the mechanism, according to which the magnetization emerges from a coherent charge motion between different t2g orbitals (dyz-dxz-dxy) of Ru3+ ions. This ult…
Ultrafast dynamics in the Lifshitz-type 5${d}$ pyrochlore antiferromagnet Cd$_{2}$Os$_{2}$O$_{7}$
我们研究了Cd $_2$ Os $_2$ O $_7$的超快动力学，这是一种显示出Lifshitz型转变的原型材料。在顺磁金属状态下，光反射率显示出亚皮秒弛豫，随后是无特征的小偏移。然而，在略低于$T_N$的反铁磁状态下，光反射率会在数百皮秒以上重新出现，这超出了有效温度模型的通常范围。我们的观测结果与Cd $_2$ Os $_2$ O $_7$的Lifshitz相变是一致的，该相变是由局域磁矩的演化驱动的.
Ultrafast laser pulse has provided a systematic way to inspect the dynamics of electrons in condensed matter systems. In this paper, by means of time-dependent density matrix renormalization group, we study an ultrafast laser driven Kondo lattice model, in which conduction electrons are strongly coupled with magnetically local moments. The single-particle spectral function due to strong correlation effects and photon emission in the non-equilibrium states under laser driving are calculated. We find laser field excited collective doublon-hole pairs and an associated transient melting of Kondo c…
Model of ultrafast demagnetization driven by spin-orbit coupling in a photoexcited antiferromagnetic insulator Cr2O3
本文从理论上研究了反铁磁绝缘体Cr $_{2}$ O $_{3}$在激光脉冲泵浦下的动态时间演化。通过求解耗散薛定谔方程，研究了从高自旋四重态到长寿命低自旋二重态的超快退磁过程。我们发现，退磁时间是数百飞秒的顺序，与最近的实验很好地吻合。通过适当调节Cr $^{3+}$多重态能级之间的能隙，可以大大减少开关时间。此外，弛豫时间还依赖于第一光激发态原子轨道的杂化。我们的研究结果表明，选择性操纵的电子结构的工程应力应变或化学取代允许有效地控制的磁状态切换的光激发绝缘过渡金属氧化物。
Ultrafast dynamics across the photoinduced three-dimensional Peierls-like insulator-metal (IM) transition in CuIr$_{2}$S$_{4}$ was investigated by means of the all-optical ultrafast multi-pulse time-resolved spectroscopy. The structural coherence of the low-$T$ broken symmetry state is strongly suppressed on a sub-picosecond timescale above a threshold excitation fluence of $F_{\mathrm{c}}\approx3$ mJ/cm$^{2}$ (at 1.55-eV photon energy) resulting in a structurally inhomogeneous transient state which persists for several-tens of picoseconds before reverting to the original low-$T$ state. The el…
Ultrafast optical pulses are an increasingly important tool for controlling quantum materials and triggering novel photo-induced phase transitions. Understanding these dynamic phenomena requires a probe sensitive to spin, charge, and orbital degrees of freedom. Time-resolved resonant inelastic X-ray scattering (trRIXS) is an emerging spectroscopic method, which responds to this need by providing unprecedented access to the finite-momentum fluctuation spectrum of photoexcited solids. In this Perspective, we briefly review state-of-the-art trRIXS experiments on condensed matter systems, as well …
The spinel-structure CuIr$_{2}$S$_{4}$ compound displays a rather unusual orbitally-driven three-dimensional Peierls-like insulator-metal transition. The low-T symmetry-broken insulating state is especially interesting due to the existence of a metastable irradiation-induced disordered weakly conducting state. Here we study intense femtosecond optical pulse irradiation effects by means of the all-optical ultrafast multi-pulse time-resolved spectroscopy. We show that the structural coherence of the low-T broken symmetry state is strongly suppressed on a sub-picosecond timescale above a threshol…
Energy density driven ultrafast electronic excitations in a cuprate superconductor
Università Cattolica del Sacro Cuore（天主教神圣之心大学）；ILAMP (Interdisciplinary Laboratories for Advanced Materials Physics)（先进材料物理跨学科实验室）；KU Leuven（荷语鲁汶大学）；Elettra - Sincrotrone Trieste S.C.p.A.（的里雅斯特电子同步加速器）；Brookhaven National Laboratory（布鲁海文国家实验室）；CNR-INO (National Institute of Optics)（意大利国家光学研究所）
Ultrafast laser excitations provide an efficient and low-power consumption alternative since different magnetic properties and topological spin states can be triggered and manipulated at the femtosecond (fs) regime. However, it is largely unknown whether laser excitations already used in data information platforms can manipulate the magnetic properties of recently discovered two-dimensional (2D) van der Waals (vdW) materials. Here we show that ultrashort laser pulses (30$-$85 fs) can not only manipulate magnetic domains of 2D-XY CrCl$_3$ ferromagnets, but also induce the formation and control …
Thermodynamics of the ultrafast phase transition of vanadium dioxide
IMDEA Nanoscience（IMDEA纳米科学研究所）；CNRS, Univ Rennes, Institut de Physique de Rennes（法国国家科学研究中心，雷恩大学，雷恩物理研究所）；The University of Tokyo（东京大学）；Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST（加泰罗尼亚纳米科学与技术研究所（ICN2），西班牙高等科学研究理事会和巴塞罗那综合理工学院）；Department of Physics and Astronomy, Aarhus University（奥胡斯大学物理与天文系）
Manipulating spin fluctuations with ultrafast laser pulses is a promising route to dynamically control collective phenomena in strongly correlated materials. However, understanding how photoexcited spin degrees of freedom evolve at a microscopic level requires a momentum- and energy-resolved characterization of their nonequilibrium dynamics. Here, we study the photoinduced dynamics of finite-momentum spin excitations in two-dimensional Mott insulators on a square lattice. By calculating the time-resolved resonant inelastic x-ray scattering cross-section, we show that an ultrafast pump above th…
