Charge and Spin Dynamics and Enantioselectivity in Chiral Molecules

Abstract

Charge and spin dynamics are addressed in chiral molecules immediately after their instantaneous coupling to an external metallic reservoir. This work describes how a spin polarization is induced in the chiral structure as a response to the charge dynamics. The dynamics indicate that chiral induced spin selectivity is an excited state phenomenon that in the transient regime can be partly captured using a simplistic single-particle description but in the stationary limit definitively shows that electron correlations, e.g., electron−vibration interactions, crucially contribute to sustain an intrinsic spin anisotropy that can lead to a nonvanishing spin selectivity. The dynamics, moreover, provide insight into enantiomer separation, due to different acquired spin polarizations.

Diamond surface engineering for molecular sensing with nitrogen—vacancy centers

“…388 Since this discovery, experiments have revealed large asymmetry in the scattering probability of polarized photoelectrons traversing thin organized films of chiral organic molecules, [388][389][390][391][392] observed spin selectivity in the conduction regime, [393][394][395][396] and measured spin-dependent charge polarization within molecules and at surfaces. [397][398][399] However, despite concurrent advances in theoretical models to describe this effect, [400][401][402][403][404][405][406] questions remain regarding the role of spin coherence and the magnitude of spin polarization accompanying electron transport within chiral molecules. Moreover, the majority of CISS measurements have relied on ferromagnetic electrodes, which may perturb observed polarizations due to the interface between ferromagnetic surfaces and the chiral material.…”

The Chiral Induced Spin Selectivity Effect -- What It Is, What It Is Not, And Why It Matters

“…The transport set-ups, in which the charge current is under scrutiny, are intuitive in the sense that there is, at least, one electrode which can be magnetized in different directions, see Figure 1, which thereby enables a control of the external magnetic conditions. Theoretical models to address the * Jonas.Fransson@physics.uu.se measured currents under such conditions have been proposed [9,[49][50][51][52][53][54][55][56][57][58], where essentially all these various models comprise a coupling between the electronic degrees of freedom to some other, both Fermionic [50,51,55,58] and Bosonic [9, 52-54, 56, 57], degrees of freedom. Also in the photospectroscopy experiments, a magnetic metal is often coupled to the sample [9] and, hence, provide a control of the magnetic conditions in a similar way.…”

Common Trends of Chiral Induced Spin Selectivity and Optical Dichroism with Varying Helix Pitch: A First-Principles Study

“…[33,34,35,2,3] Most theoretical studies indicate that diamagnetic molecules made of hydrogen and main group elements in the periodic table like carbon, nitrogen, and oxygen with very weak intrinsic SO interaction lead to a magnitude of the CISS effect which is orders of magnitude lower than what is observed in experiment, which implies that to reproduce the experimental magnitude of CISS, one has to invoke a yet unexplained large effective value of SO coupling. [36,37,38,39] To help explain these discrepancies, the role of molecule-electrode interfaces [31,32,30,26,40,41] and electron-phonon coupling has been discussed [42,23,43,44,45,46,47], despite these efforts, no unifying theoretical explanation for CISS has so far emerged [48].…”