Control of Atomic Collisions by Laser Polarization

Schmidt, Thomas A.; Figl, Cristina; Grimpe, A.; Großer, J.; Hoffmann, O.; Rebentrost, F.

doi:10.1103/physrevlett.92.033201

Cited by 11 publications

(9 citation statements)

References 24 publications

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“…The main experimental challenge, the superposition of a laser beam, an energetic ion or electron beam, and a target has been mastered very recently [6]. The possible control of slow atom-atom collisions by laser light has been demonstrated with a somewhat different setup [7]. On the theoretical side refined methods for the description of laserassisted collisions have been worked out, implemented and tested on prototype scattering systems.…”

Section: Introductionmentioning

confidence: 99%

Laser-field-induced modifications of electron-transfer processes in ion-atom collisions

Kirchner

2004

Phys. Rev. A

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Electron transfer in the presence of a laser field is explored for the prototype collision system He 2+ -H͑1s͒ on the basis of a quantum-mechanical calculation. At collision energies E P ജ 2 keV/ amu the capture probabilities are found to be conisderably enhanced or suppressed depending on the exact synchronization of the timedependent projectile and laser interactions. At lower collision energies the total capture cross section is strongly enhanced irrespective of the relative phase between both fields. This enhancement should be directly observable in future experiments.

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Section: Introductionmentioning

confidence: 99%

Laser-field-induced modifications of electron-transfer processes in ion-atom collisions

Kirchner

2004

Phys. Rev. A

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“…LiVSe2 was found to be a paramagnetic metal down to 2 K. Transition metal compounds with a geometrically frustrated lattice, such as a triangular and a pyrochlore lattice, often form a valence bond solid (VBS) state at low temperatures. When the t 2g orbitals are partially occupied, utilizing orbital degrees of freedom, complex "molecular" clusters in a spin singlet state are often formed: trimer in LiVO 2 [1,2,3,4,5], heptamer in AlV 2 O 4 [6], helical dimer in MgTi 2 O 4 [7] and octamer in CuIr 2 S 4 [8]. A VBS state was found also in organic systems with geometrical frustration [9].…”

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confidence: 99%

Anomalous Metallic State in the Vicinity of Metal to Valence-Bond Solid Insulator Transition inLiVS2

et al. 2009

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We investigate LiVS2 and LiVSe2 with a triangular lattice as itinerant analogues of LiVO2, known for the formation of valence bond solid (VBS) state out of S = 1 frustrated magnet. LiVS2, which is located at the border between a metal and a correlated insulator, shows a first ordered transition from a paramagnetic metal to a VBS insulator at Tc ∼ 305 K upon cooling. The presence of VBS state in the close vicinity of insulator-metal transition may suggest the importance of itinerancy in the formation of VBS state. We argue that the high temperature metallic phase of LiVS2 has a pseudo-gap, likely originating from the VBS fluctuation. LiVSe2 was found to be a paramagnetic metal down to 2 K. A question that arises is whether or not similar melting of the VBS state and appearance of exotic metallic phases can occur in inorganic frustrated systems. In the inorganic systems, however, application of an external pressure is expected not to melt but to stabilize VBS due to a predominant volume effect. In CuIr 2 S 4 , the lattice shrinks appreciably in the VBS perhaps due to the formation of strongly bonded singlet molecules and the VBS can be stabilized through -pV (p : pressure, V : volume) term in the corresponding free energy [11][12]. Effects of negative pressure on the VBS states of inorganic systems, on the other hand, have not been investigated so far.The inorganic LiVO 2 in which the magnetic V 3+ ions (3d 2 , S = 1) form a triangular lattice is known to be a paramagnetic insulator with strong antiferromagnetic interactions between the localized S = 1 moments at high temperatures. Upon cooling, at T c ∼ 500 K, LiVO 2 exhibits a first ordered phase transition to a VBS state with a characteristic spin gap of ∼ 1600 K, evidenced by the formation of vanadium trimers. With this system, one can apply "negative" pressure by replacing oxygens with larger anions such as S and Se [13,14,16]. More over, the negative pressure may increase the overlap between V 3d and p-orbital (O 2p, S 3p, and Se 4p), and increase the electronic band width. Thus, this vanadium-based triangular system provides a good opportunity to study effects of negative pressure on VBS states in inorganic materials.In this Letter, we demonstrate that LiVS 2 is indeed an itinerant analogue of LiVO 2 with suppressed VBS. We found that in LiVS 2 a phase transition from a paramagnetic metal to a trimer VBS insulator occurs at T c ∼ 305 K that is lower than that of LiVO 2 . In LiVSe 2 with highest negative pressure, the phase transition is suppressed down to 2 K. In the high temperature metallic phase of LiVS 2 , strong temperature dependence of the bulk susceptibility, χ, was observed, which is similar to the pseudo-gap behavior found in underdoped superconducting cuprates. We argue this is an evidence for a pseudo-gap formation by short-range spin singlet fluctuations in the paramagnetic metallic phase of LiVS 2 .Powder samples of LiVS 2 , LiVSe 2 and their solid solution LiVS 2−x Se x were prepared by a soft-chemical method followed by a solid-state reactio...

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“…Metal-insulator transitions with the formation of unusual structures are observed in many spinels. The recent examples are MgTi 2 O 4 [2], CuIr 2 S 4 [3] or AlV 2 O 4 [4]. Structural studies have shown that in all these cases rather unusual structural modifications take place, which often can be described as the formation of molecular clusters.…”

Section: Formation Of Dimers In Spinelsmentioning

confidence: 99%

“…Structural studies have shown that in all these cases rather unusual structural modifications take place, which often can be described as the formation of molecular clusters. In MgTi 2 O 4 there appears a "chiral" structure [2], in CuIr 2 S 4 Ir octamers are formed [3], but both these phenomena can in fact be explained by the formation of Ti or Ir singlet dimers, which in a frustrated lattice of B-sites of a spinel finally give rise to these chiral or octamer structures [5]. And in AlV 2 O 4 the molecular clusters formed consist of 7 vanadiums -real large "heptamer molecules".…”

Section: Formation Of Dimers In Spinelsmentioning

confidence: 99%

Novel electronic states close to Mott transition in low-dimensional and frustrated systems

Khomskii¹

2011

J. Phys.: Conf. Ser.

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Recent studies demonstrated that there may appear different novel states in correlated systems close to localized-itinerant crossover. Especially favourable conditions for that are met in low-dimensional and in frustrated systems. In this paper I discuss on concrete examples some of such novel states. In particular, for some spinels and triangular systems there appears a "partial Mott transition", in which first some finite clusters (dimers, trimes, tetramers, heptamers) go over to the itinerant regime, and the real bulk Mott transition occurs only later. Also some other specific possibilities in this crossover regime are shortly discussed, such as spin-Peierls-Peierls transition in TiOCl, spontaneous charge disproportionation in some cases, etc.

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Control of Atomic Collisions by Laser Polarization

Abstract: Atomic collision pairs in a light field form a microscopic interferometer. The light acts as the beam splitter and controls at the same time the amplitudes and phases of the interfering waves. We demonstrate the complete tunability using linear and elliptic polarization.

Cited by 11 publications

References 24 publications

Laser-field-induced modifications of electron-transfer processes in ion-atom collisions

Laser-field-induced modifications of electron-transfer processes in ion-atom collisions

Anomalous Metallic State in the Vicinity of Metal to Valence-Bond Solid Insulator Transition inLiVS2

Novel electronic states close to Mott transition in low-dimensional and frustrated systems

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