相关实验视频

Updated: Sep 14, 2025

Direct Imaging of Laser-driven Ultrafast Molecular Rotation

Direct Imaging of Laser-driven Ultrafast Molecular Rotation

Published on: February 4, 2017

超快旋转动力学:激光诱导的交换参数修改的作用

S Mankovsky¹, S Polesya¹, H Ebert¹

¹Department of Chemistry/Phys. Chemistry, LMU Munich, Butenandtstrasse 11, D-81377 Munich, Germany.

Journal of physics. Condensed matter : an Institute of Physics journal

|July 18, 2025

概括

超短激光脉冲极大地改变材料的电子结构,影响磁性. 这项研究揭示了激光诱导的电子转换显著改变交换合,影响去磁化和放松动态.

科学领域:

凝聚物质物理学凝聚物质物理学
超快的磁力超快的磁力
计算材料科学科学计算材料科学

背景情况:

激光诱导的去磁化是磁性材料中的一个关键现象.
现有的模型往往忽略了激光修改的电子结构对磁相互作用的影响.
旋转转的转换与斯通纳式机制有关,而横旋转的波动通常由海森伯格哈密尔顿式描述.

研究的目的:

为了研究激光诱导的电子结构修改对交换合参数的影响.
探索旋转翻转和旋转保护电子过渡的作用.
了解对去磁化和放松过程的影响.

主要方法:

利用时间依赖密度功能理论 (TD-DFT) 在超短激光脉冲下建模电子结构演变.
采用两步方案:首先,TD-DFT用于电子结构,然后计算海森堡哈密尔顿参数.
分析时间依赖的电子结构,以确定交换合的变化.

主要成果:

由于激光诱导的电子状态脱落,在 femtosecond 时间尺度上显示了交换合参数的显著修改.
观察到这些变化缓慢减弱 (分秒/小秒时间尺度),表明持久的影响.
显示了激光诱导的电子结构变化对自旋格子合参数的强烈影响.

结论:

激光诱导的电子转换极大地影响了交换合,这对于理解超快速去磁化至关重要.
电子结构的修改对马格农能量和放松动态有重大影响.
这项工作强调了在超快磁现象和自旋晶格相互作用理论中考虑激光修改电子结构的重要性.

关键词:

电子结构电子结构交换合参数交换合参数超快的去磁化方式

更多相关视频

Spin Saturation Transfer Difference NMR SSTD NMR: A New Tool to Obtain Kinetic Parameters of Chemical Exchange Processes

Spin Saturation Transfer Difference NMR SSTD NMR: A New Tool to Obtain Kinetic Parameters of Chemical Exchange Processes

Published on: November 12, 2016

Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization

Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization

Published on: August 6, 2018

相关概念视频

Spin–Spin Coupling Constant: Overview

Spin–Spin Coupling Constant: Overview

In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...

NMR Spectroscopy: Spin–Spin Coupling

NMR Spectroscopy: Spin–Spin Coupling

The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved...

Double Resonance Techniques: Overview

Double Resonance Techniques: Overview

Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
Spin decoupling is usually achieved by...

Nuclear Overhauser Enhancement (NOE)

Nuclear Overhauser Enhancement (NOE)

Irradiation of a spin-active nucleus causes an increase or decrease in the signal intensity of neighboring nuclei that are not necessarily chemically bonded or involved in J-coupling. This phenomenon, called the Nuclear Overhauser Enhancement (NOE), results from through-space interactions between the nuclear spins. The NOE effect decreases with increasing internuclear distance and is generally not observed beyond 4 angstroms. In NOE, dipole-dipole interactions between neighboring...

Atomic Nuclei: Types of Nuclear Relaxation

Atomic Nuclei: Types of Nuclear Relaxation

Nuclear relaxation restores the equilibrium population imbalance and can occur via spin–lattice or spin–spin mechanisms, which are first-order exponential decay processes.
In spin–lattice or longitudinal relaxation, the excited spins exchange energy with the surrounding lattice as they return to the lower energy level. Among several mechanisms that contribute to spin–lattice relaxation, magnetic dipolar interactions are significant. Here, the excited nucleus transfers...

Spin–Spin Coupling: One-Bond Coupling

Spin–Spin Coupling: One-Bond Coupling

Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the pair of bonding electrons. While nuclei polarize their electrons to the opposite spins, the bonding electron pair has opposite spins. Configurations with antiparallel nuclear spins are expected to be lower in energy. When coupling makes antiparallel states more favorable, J is considered to have a positive value. The one-bond coupling constant, 1J,...