arXiv:1212.2895 · Physical Review A

Spin-polarized electrons produced by strong-field ionization

Ingo Barth, Olga V. Smirnova

Published Jul 1, 2013• 116 citations

Abstract

We show that ionization of noble gas atoms by a strong infrared circularly polarized laser field under standard experimental conditions can yield electrons with up to 100$%$ spin polarization in energy-resolved measurements. Spin polarization arises due to the interplay of the electron-core entanglement and the sensitivity of ionization in circularly polarized fields to the sense of electron rotation in the initial state.

DOI: 10.1103/physreva.88.013401

Related papers

Spin Polarization in Strong-Field Ionization as Sensor of Trapped Electron Orbits

Linxuan Zhang, Stefanos Carlström, Olga V. Smirnova +2 more

Physical Review LettersNov 6, 20254 citations

Producing spin-polarized photoelectrons by using the momentum gate in strong-field ionization experiments

Kunlong Liu, Klaus Renziehausen, Ingo Barth

Physical Review AJun 13, 201731 citations

Electron spin polarization in strong-field ionization and the effect of spin in attoclock measurements

Felipe Morales, Jivesh Kaushal, Alexander Hartung +11 more

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)Jun 1, 20170 citations

Towards atom-scale spin-selective electron emitters based on strong-field Freeman resonant ionization

Shengliang Xu, Qingbin Zhang, Xianglong Fu +5 more

Physical Review ADec 31, 202010 citations

Spin-orientation-resolved attosecond chronoscopy in strong field ionization

Minqqing Liu, Wei‐Chao Jiang

arXiv:2305.00732May 1, 20230 citations

Spatially and temporally controlling electron spin polarization in strong-field ionization using orthogonal two-color laser fields

Meng Han, Peipei Ge, Mingming Liu +2 more

Physical Review AFeb 4, 201918 citations

arXiv:1212.2895 · Physical Review A

Spin-polarized electrons produced by strong-field ionization

Ingo Barth, Olga V. Smirnova

Published Jul 1, 2013• 116 citations

arXiv HTML PDF

Abstract

We show that ionization of noble gas atoms by a strong infrared circularly polarized laser field under standard experimental conditions can yield electrons with up to 100

%

spin polarization in energy-resolved measurements. Spin polarization arises due to the interplay of the electron-core entanglement and the sensitivity of ionization in circularly polarized fields to the sense of electron rotation in the initial state.

DOI: 10.1103/physreva.88.013401

Related papers

Spin Polarization in Strong-Field Ionization as Sensor of Trapped Electron Orbits

Linxuan Zhang, Stefanos Carlström, Olga V. Smirnova +2 more

We show how spin polarization of photoelectrons produced in strong-field ionization of noble-gas atoms can be used to detect highly unexpected electron orbits created in strong, circularly polarized near-infrared fields. In such fields, ionization is expected to generate photoelectrons rapidly moving away from the ionic core, freezing their initial spin due to the short-range nature of the spin-orbit interaction between the photoelectron and the core. However, we find clear evidence of spin flips in the photoelectron spectra at low photoelectron energies and confirm that they happen because a photoelectron has been trapped near the core. The presence of such highly unexpected orbits explains the marked deviations between the recent experimental measurements of spin polarization [Nat. Photonics 10, 526 (2016)NPAHBY1749-488510.1038/nphoton.2016.109] and simulations with frozen spin.We show how spin polarization of photoelectrons produced in strong-field ionization of noble-gas atoms can be used to detect highly unexpected electron orbits created in strong, circularly polarized near-infrared fields. In such fields, ionization is expected to generate photoelectrons rapidly moving away from the ionic core, freezing their initial spin due to the short-range nature of the spin-orbit interaction between the photoelectron and the core. However, we find clear evidence of spin flips in the photoelectron spectra at low photoelectron energies and confirm that they happen because a photoelectron has been trapped near the core. The presence of such highly unexpected orbits explains the marked deviations between the recent experimental measurements of spin polarization [Nat. Photonics 10, 526 (2016)NPAHBY1749-488510.1038/nphoton.2016.109] and simulations with frozen spin.

Physical Review LettersNov 6, 20254 citations

Producing spin-polarized photoelectrons by using the momentum gate in strong-field ionization experiments

Kunlong Liu, Klaus Renziehausen, Ingo Barth

The ionization of the prealigned nitric oxide molecule by strong circularly polarized laser fields is studied via theoretical simulations of the spin-resolved photoelectron momentum distributions by solving numerically the three-dimensional time-dependent Schr\"odinger equation. Due to the spin-orbit entanglement in the ground state of nitric oxide and the sensitivity of the tunnel ionization of its doubly degenerate valence $2{\ensuremath{\pi}}_{\ifmmode\pm\else\textpm\fi{}}$ orbitals carrying opposite electron ring currents to the sense of the laser-field rotation, the momentum-resolved spin-polarized photoelectrons are produced. We show that the spin polarization exhibits strong dependence on the kinetic energy as well as the emitting angle of the photoelectron. In addition to the laser control, the momentum gate in strong-field experiments would enable full control of the spin polarization.The ionization of the prealigned nitric oxide molecule by strong circularly polarized laser fields is studied via theoretical simulations of the spin-resolved photoelectron momentum distributions by solving numerically the three-dimensional time-dependent Schr\"odinger equation. Due to the spin-orbit entanglement in the ground state of nitric oxide and the sensitivity of the tunnel ionization of its doubly degenerate valence $2{\ensuremath{\pi}}_{\ifmmode\pm\else\textpm\fi{}}$ orbitals carrying opposite electron ring currents to the sense of the laser-field rotation, the momentum-resolved spin-polarized photoelectrons are produced. We show that the spin polarization exhibits strong dependence on the kinetic energy as well as the emitting angle of the photoelectron. In addition to the laser control, the momentum gate in strong-field experiments would enable full control of the spin polarization.

Physical Review AJun 13, 201731 citations

Electron spin polarization in strong-field ionization and the effect of spin in attoclock measurements

Felipe Morales, Jivesh Kaushal, Alexander Hartung +11 more

Summary form only given. Spin plays a fundamental role in the electronic structure of matter, from single atoms and molecules through to condensed matter. However, spin dynamics and the spin response of electrons to ultra-short, strong laser pulses has remained largely unexplored until today. In 2011 and 2013, pioneering theoretical work [1, 2] extended the fundamental PPT theory [3] to treat ionization of p+ and p” electrons by circular fields. This work predicted the sensitivity of ionization probabilities in strong field ionization using circular fields to the magnetic quantum number, showing that counter rotating electrons can tunnel ionize easier. It also predicted the possibility to obtain spin polarized electrons from strong, circularly polarized fields with a high degree of efficiency. The preference of ionization was later confirmed experimentally by [4], however, the experiment in [4] did not provide a confirmation of the spin polarization predictions.Summary form only given. Spin plays a fundamental role in the electronic structure of matter, from single atoms and molecules through to condensed matter. However, spin dynamics and the spin response of electrons to ultra-short, strong laser pulses has remained largely unexplored until today. In 2011 and 2013, pioneering theoretical work [1, 2] extended the fundamental PPT theory [3] to treat ionization of p+ and p” electrons by circular fields. This work predicted the sensitivity of ionization probabilities in strong field ionization using circular fields to the magnetic quantum number, showing that counter rotating electrons can tunnel ionize easier. It also predicted the possibility to obtain spin polarized electrons from strong, circularly polarized fields with a high degree of efficiency. The preference of ionization was later confirmed experimentally by [4], however, the experiment in [4] did not provide a confirmation of the spin polarization predictions.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)Jun 1, 20170 citations

Towards atom-scale spin-selective electron emitters based on strong-field Freeman resonant ionization

Shengliang Xu, Qingbin Zhang, Xianglong Fu +5 more

To produce electrons with well-defined spin via photoionization, realizing orbital-resolved ionization is the prerequisite due to spin-orbital coupling. In this paper, we numerically and experimentally demonstrate that the electrons emitted from two original energy degenerated orbitals ( $j=3/2, m=1$ and $j=3/2, m=\ensuremath{-}1$) of Xe atoms can be well separated in the energy domain through selectively achieving Freeman resonance during strong-field ionization using a circularly polarized laser field. This orbital resolved Freeman resonant ionization leads to strong spin sensitivity without the need of fine laser frequency and intensity tuning. This result enables the production of high-degree spin-polarized electrons by energy gating, which provides a unique degree of freedom for advancing many promising applications.To produce electrons with well-defined spin via photoionization, realizing orbital-resolved ionization is the prerequisite due to spin-orbital coupling. In this paper, we numerically and experimentally demonstrate that the electrons emitted from two original energy degenerated orbitals ($j=3/2, m=1$ and $j=3/2, m=\ensuremath{-}1$) of Xe atoms can be well separated in the energy domain through selectively achieving Freeman resonance during strong-field ionization using a circularly polarized laser field. This orbital resolved Freeman resonant ionization leads to strong spin sensitivity without the need of fine laser frequency and intensity tuning. This result enables the production of high-degree spin-polarized electrons by energy gating, which provides a unique degree of freedom for advancing many promising applications.

Physical Review ADec 31, 202010 citations

Spin-orientation-resolved attosecond chronoscopy in strong field ionization

Minqqing Liu, Wei‐Chao Jiang

Attosecond chronoscopy represents a major breakthrough in the study of ultrafast phenomena and has the potential to revolutionize our understanding of the fundamental physics of matter. We theoretically investigate the spin-orientation-resolved attosecond chronoscopy for the first time by the circular RABBIT technique for Kr atoms. Due to the spin-orbit interaction and the sensitivity of ionization in circularly polarized fields to the sense of electron rotation in the initial state, the spin-resolved ionization rates of photoelectrons emitted from $^2P_{1/2}$ and $^2P_{3/2}$ channels can be expressed via $m$ -resolved ionization rates of initial state, where $m$ is the orbital magnetic quantum number. We demonstrate that the yields difference between spin-up and spin-down photoelectrons from each channel are closely associated with the different behaviors of corresponding Wigner time delay. We find that the Wigner time delay between spin-up and spin-down photoelectrons in the polarization plane can reach several tens of attoseconds in the co-rotating geometry, but a few attoseconds in the counter-rotating geometry. Our approach opens up a new avenue for probing the spin-dependent behavior of Wigner time delay, and lays the foundation for spin-orientation-resolved attosecond chronoscopy, which can be verified by the current experimental techniques.Attosecond chronoscopy represents a major breakthrough in the study of ultrafast phenomena and has the potential to revolutionize our understanding of the fundamental physics of matter. We theoretically investigate the spin-orientation-resolved attosecond chronoscopy for the first time by the circular RABBIT technique for Kr atoms. Due to the spin-orbit interaction and the sensitivity of ionization in circularly polarized fields to the sense of electron rotation in the initial state, the spin-resolved ionization rates of photoelectrons emitted from $^2P_{1/2}$ and $^2P_{3/2}$ channels can be expressed via $m$-resolved ionization rates of initial state, where $m$ is the orbital magnetic quantum number. We demonstrate that the yields difference between spin-up and spin-down photoelectrons from each channel are closely associated with the different behaviors of corresponding Wigner time delay. We find that the Wigner time delay between spin-up and spin-down photoelectrons in the polarization plane can reach several tens of attoseconds in the co-rotating geometry, but a few attoseconds in the counter-rotating geometry. Our approach opens up a new avenue for probing the spin-dependent behavior of Wigner time delay, and lays the foundation for spin-orientation-resolved attosecond chronoscopy, which can be verified by the current experimental techniques.

arXiv:2305.00732May 1, 20230 citations

Spatially and temporally controlling electron spin polarization in strong-field ionization using orthogonal two-color laser fields

Meng Han, Peipei Ge, Mingming Liu +2 more

We propose a scheme to produce spatially and temporally controlled spin-polarized photoelectrons by strong-field ionization of atoms. We calculate the momentum-resolved electron spin polarization from two spin-orbit coupled ionic states ( $J=1/2$ and $J=3/2$ ) of krypton atoms in orthogonal two-color laser fields using the strong-field approximation, and obtain the instantaneous spin-polarization degree. With this scheme, the spin-up and -down photoelectrons can be well separated in the space, and the spin polarization is controlled on the sub-laser-cycle timescale. This study illustrates and reveals the mechanism of the generation of spin-polarized photoelectrons with an arbitrary spatially and temporally tailored laser field. We expect this work has implications for controlling the spatiotemporal spin polarization in strong-field physics.We propose a scheme to produce spatially and temporally controlled spin-polarized photoelectrons by strong-field ionization of atoms. We calculate the momentum-resolved electron spin polarization from two spin-orbit coupled ionic states ($J=1/2$ and $J=3/2$) of krypton atoms in orthogonal two-color laser fields using the strong-field approximation, and obtain the instantaneous spin-polarization degree. With this scheme, the spin-up and -down photoelectrons can be well separated in the space, and the spin polarization is controlled on the sub-laser-cycle timescale. This study illustrates and reveals the mechanism of the generation of spin-polarized photoelectrons with an arbitrary spatially and temporally tailored laser field. We expect this work has implications for controlling the spatiotemporal spin polarization in strong-field physics.

Physical Review AFeb 4, 201918 citations

We show that ionization of noble gas atoms by a strong infrared circularly polarized laser field under standard experimental conditions can yield electrons with up to 100

%

j=3/2, m=1

and $j=3/2, m=\ensuremath{-}1$) of Xe atoms can be well separated in the energy domain through selectively achieving Freeman resonance during strong-field ionization using a circularly polarized laser field. This orbital resolved Freeman resonant ionization leads to strong spin sensitivity without the need of fine laser frequency and intensity tuning. This result enables the production of high-degree spin-polarized electrons by energy gating, which provides a unique degree of freedom for advancing many promising applications.

^2P_{1/2}

and

^2P_{3/2}

channels can be expressed via

m

-resolved ionization rates of initial state, where

m

is the orbital magnetic quantum number. We demonstrate that the yields difference between spin-up and spin-down photoelectrons from each channel are closely associated with the different behaviors of corresponding Wigner time delay. We find that the Wigner time delay between spin-up and spin-down photoelectrons in the polarization plane can reach several tens of attoseconds in the co-rotating geometry, but a few attoseconds in the counter-rotating geometry. Our approach opens up a new avenue for probing the spin-dependent behavior of Wigner time delay, and lays the foundation for spin-orientation-resolved attosecond chronoscopy, which can be verified by the current experimental techniques.

J=1/2

and

J=3/2

) of krypton atoms in orthogonal two-color laser fields using the strong-field approximation, and obtain the instantaneous spin-polarization degree. With this scheme, the spin-up and -down photoelectrons can be well separated in the space, and the spin polarization is controlled on the sub-laser-cycle timescale. This study illustrates and reveals the mechanism of the generation of spin-polarized photoelectrons with an arbitrary spatially and temporally tailored laser field. We expect this work has implications for controlling the spatiotemporal spin polarization in strong-field physics.