Chiral systems exist in two forms (enantiomers) which are each-others mirror image. More specifically they can only by superimposed onto each other seamlessly through a parity-reversal-symmetry operation, that is, chiral systems break intrinsically parity-reversal (space-inversion) symmetry. Imposing in addition a violation of time-reversal symmetry by e.g. a magnetic field leads to bi-linear anisotropies in the materials properties such as electrical resistivity or dielectric function. These so-called magnetochiral anisotropies are of scalable magnitude provided the associated mediating particles (electrons, photons etc.) experience the structural chirality (cf. extension of wave-function vs. characteristic chiral lengthscale).
In nature there are intrinsically chiral systems existing such as chiral molecules, DNA, etc., however, their chiral structure cannot be altered and is therefore limited. A completely new nanoscale materials-base is provided by so-called topologically chiral systems, that is, nano-sized materials which are brought into a chiral form (e.g. a straight wire formed into a coil). These are a sub-class of metamaterials which are broadly known for their unconventional material non-intrinsic properties (e.g. negative refractive index).
Our main current research addresses the study of electronic and spin transport as well as optoelectronic effects in nanosized topologically chiral elemental metals including noble metals, ferromagnets, and superconductors. For this, the metals are shaped into well-structured nano-sized helices by a physical growing technique. The fundamental properties arising from the unique helical, chiral shape on the nanoscale are investigated by electrical transport and optical means without and with static and transient magnetic fields applied.
The produced nanohelices are studied in terms of their operation as plasmonic helical antenna, and their magnetochiral-anisotropy response in electrical transport and optical reflection/transmission also in view of correlated ferromagnetic and superconducting states, all of which are tailored in terms of pitch, diameter and material of which the nanohelix consists.
These properties are exploited and benchmarked aiming for beyond the current state-of-the-art electronic and optoelectronic technology platforms.
Key-words: chiral, topologically chiral, nanohelix, metal, magnetochiral anisotropy, electrical
transport, optical antenna, magnetotransport, magnetooptics
C. Train, R. Gheorghe, V. Krstić, L.M. Chamorea, N.S. Ovanesyan, G.L.J.A. Rikken, M. Gruselle, M. Verdaguer
“Strong magneto-chiral dichroism in enantiopure chiral ferromagnets”
Nature Materials 7, 729 (2008)
B.A. van Tiggelen, G.L.J.A. Rikken, V. Krstić
“Momentum transfer from quantum vacuum to magnetoelectric matter”
Phys. Rev. Lett. 96, 130402 (2006)
G.L.J.A. Rikken, B.A. van Tiggelen, V. Krstić, G. Wagnière
‘Light induced dynamic magnetochiral anisotropy”
Chem. Phys. Lett. 403, p. 298-302 (2005)
V. Krstić, G. Wagnière, G.L.J.A. Rikken
“Magneto-dynamics of chiral carbon nanotubes”
Chem. Phys. Lett. 390, p. 25-28 (2004)
V. Krstić, S. Roth, M. Burghard, K. Kern, G.L.J.A. Rikken
“Magneto-chiral anisotropy in charge transport through single-walled carbon nanotubes”
J. Chem. Phys. 117 , p. 11315-11319 (2002)
S. Roth, V. Krstić, G.L.J.A. Rikken
“Quantum transport in carbon nanotubes”
Curr. Appl. Phys. 2, p. 155-161 (2002)
V. Krstić, G.L.J.A. Rikken
“Magneto-chiral anisotropy of the free electron on a helix”
Chem. Phys. Lett. 364, p. 51-56 (2002)
G.L.J.A. Rikken, E. Raupach, V. Krstić, S. Roth
Molec. Phys. 100, p. 1155-1160 (2002)