Influence of long-range interactions on charge ordering phenomena on a square lattice

Rademaker, Louk; Pramudya, Yohanes; Zaanen, Jan; Dobrosavljević, Vladimir

doi:10.1103/physreve.88.032121

Cited by 36 publications

(44 citation statements)

References 43 publications

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“…Monte Carlo simulations (Fig. 4e), using the vacancy-vacancy interactions discussed above, are in very good agreement with the experiment and show that this system provides an ideal physical realization of a lattice gas model, for which stripe phases are expected 22 .…”

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confidence: 72%

A kilobyte rewritable atomic memory

et al. 2016

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The advent of devices based on single dopants, such as the single atom transistor 1 , the single spin magnetometer 2,3 and the single atom memory 4 , motivates the quest for strategies that permit to control matter with atomic precision. Manipulation of individual atoms by means of low-temperature scanning tunnelling microscopy 5 provides ways to store data in atoms, encoded either into their charge state 6,7 , magnetization state 8-10 or lattice position 11 . A defining challenge at this stage is the controlled integration of these individual functional atoms into extended, scalable atomic circuits. Here we present a robust digital atomic scale memory of up to 1 kilobyte (8,000 bits) using an array of individual surface vacancies in a chlorine terminated Cu(100) surface. The memory can be read and rewritten automatically by means of atomic scale markers, and offers an areal density of 502 Terabits per square inch, outperforming state-of-the-art hard disk drives by three orders of magnitude. Furthermore, the chlorine vacancies are found to be stable at temperatures up to 77 K, offering prospects for expanding large-scale atomic assembly towards ambient conditions.Since the first demonstration of atom manipulation, 25 years ago 5 , the preferred approach for assembling atomic arrangements has been the lateral positioning of atoms or molecules evaporated onto a flat metal surface, most notably the (111) crystal surface of copper [12][13][14][15] . While ideal for experiments comprising up to several hundreds of constituents, the absence of a large-scale defect-free detectable grid on this surface prohibits the construction of architectures involving correlated lattice-placement of atoms separated by more than a few nanometres. Moreover, thermal motion of the adatoms restricts the technique to temperatures below 10 K. As we demonstrate below, we find that manipulation of missing atoms in a surface (vacancies) 16 , as opposed to additional atoms atop, permits a dramatic leap forward in our capability to build functional devices on the atomic scale.To this purpose, we take advantage of the self-assembly of chlorine atoms on the Cu(100) surface [17][18][19][20] , forming a flat two-dimensional lattice with several convenient properties. First, it provides large areas of a perfect template grid, with a controllable coverage of vacancies. Second, the chlorine lattice remains stable up to a large density of vacancies and up to relatively high temperature (77 K). And third, critical for our purpose, the precise location of the vacancies can be manipulated by STM with a very high level of control (and without the need to pick-up atoms with the tip, i.e. vertical atom manipulation). As we show below, these properties allow us to position thousands of vacancies at predefined atomic sites in a reasonable timeframe.The chlorinated copper surface is prepared in ultra-high vacuum through the evaporation of anhydrous CuCl 2 powder heated to 300 °C onto a clean Cu(100) crystal surface. The crystal is pre-heated to 100-150 °C prior...

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confidence: 72%

A kilobyte rewritable atomic memory

et al. 2016

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“…The transverse rods shrink to the minimum size of 1 bisoliton, then the CIs start to compete with the confinement force, so bisolitons start to elongate and, at some V C , the Ising order is destroyed. For the highest values of CIs a Wigner "liquid" of individual solitons is observed, which case was studied in [48][49][50] . …”

Section: System Of Charged Solitonsmentioning

confidence: 99%

Phase transitions in ensembles of solitons induced by an optical pumping or a strong electric field

Karpov

2016

Phys. Rev. B

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The latest trend in studies of modern electronically and/or optically active materials is to provoke phase transformations induced by high electric fields or by short (femtosecond) powerful optical pulses. The systems of choice are cooperative electronic states whose broken symmetries give rise to topological defects. For typical quasi-one-dimensional architectures, those are the microscopic solitons taking from electrons the major roles as carriers of charge or spin. Because of the longrange ordering, the solitons experience unusual super-long-range forces leading to a sequence of phase transitions in their ensembles: the higher-temperature transition of the confinement and the lower one of aggregation into macroscopic walls. Here we present results of an extensive numerical modeling for ensembles of both neutral and charged solitons in both two-and three-dimensional systems. We suggest a specific Monte Carlo algorithm preserving the number of solitons, which substantially facilitates the calculations, allows to extend them to the three-dimensional case and to include the important long-range Coulomb interactions. The results confirm the first confinement transition, except for a very strong Coulomb repulsion, and demonstrate a pattern formation at the second transition of aggregation.

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“…On the other hand we expect that spinexciton interactions destabilize the coexistence phases, since these interactions generally lead to frustration effects. One could also wonder what happens if one includes longer-ranged interactions for the excitons, with the possibility of exciton stripes and incommensurate charge ordered phases 36 . Next, we are dealing with first order phase transitions where small changes may have severe consequences.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…The maximal difference possible equals Min(ρ, 1 − ρ), so (34), the checkerboard order parameter, equation (35), the superfluid density, equation (36), the phase coherence, equation (37), and the ratio signaling phase separation according to equation (39), 0 means complete phase separation, 1 means no phase separation. Notice that the prominent line at ρ = 0.5 signals the checkerboard phase.…”

Section: B Simulated Annealingmentioning

confidence: 99%

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Exciton condensation in strongly correlated electron bilayers

et al. 2013

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We studied the possibility of exciton condensation in Mott insulating bilayers. In these strongly correlated systems an exciton is the bound state of a double occupied and empty site. In the strong coupling limit the exciton acts as a hard-core boson. Its physics are captured by the exciton t − J model, containing an effective XXZ model describing the exciton dynamics only. Using numerical simulations and analytical mean field theory we constructed the ground state phase diagram. Three homogeneous phases can be distinguished: the antiferromagnet, the exciton checkerboard crystal and the exciton superfluid. For most model parameters, however, we predict macroscopic phase separation between these phases. The exciton superfluid exists only for large exciton hopping energy. Additionally we studied the collective modes and susceptibilities of the three phases. In the superfluid phase we find the striking feature that the bandwidth of the spin-triplet excitations, potentially detectable by resonant inelastic x-ray scattering (RIXS), is proportional to the superfluid density. The superfluid phase mode is visible in the charge susceptibility, measurable by RIXS or electron energy loss spectroscopy (EELS).

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Influence of long-range interactions on charge ordering phenomena on a square lattice

Cited by 36 publications

References 43 publications

A kilobyte rewritable atomic memory

A kilobyte rewritable atomic memory

Phase transitions in ensembles of solitons induced by an optical pumping or a strong electric field

Exciton condensation in strongly correlated electron bilayers

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