We report a systematic study of the transport properties of coupled one-dimensional metallic chains as a function of the number of parallel chains. When the number of parallel chains is less than 2000, the transport properties show power-law behavior on temperature and voltage, characteristic for one-dimensional systems.PACS numbers: 72.15. Nj, 74.78.Na, 71.45.Lr Electron-electron interactions in one-dimensional (1D) metals exhibit dramatically different behavior from three-dimensional metals, in which electrons form a Fermi liquid. Depending on the details of the electronelectron interaction, several phases are possible, such as a Luttinger Liquid (LL) or a 1D Wigner crystal (WC). The tunneling density-of-states (TDOS) of these 1D phases exhibit power-law behavior on the larger one of either eV or k B T [1, 2, 3], with V the voltage and T the temperature.

No abstract

Charge-density-wave (CDW) dynamics is studied on a submicron length scale in NbSe 3 and o-TaS 3 . Regions of negative absolute resistance are observed in the CDW sliding regime at sufficiently low temperatures. The origin of the negative resistance is attributed to the different forces that the deformed CDW and quasiparticles feel: the force on the CDW is merely caused by a difference of the electric potentials, while the quasiparticle current is governed by a difference of the electrochemical potentials. DOI: 10.1103/PhysRevLett.87.126401 PACS numbers: 71.45.Lr, 72.15.Nj A periodic modulation of the conduction electron density is commonly observed in low-dimensional conductors [1]. This charge-density-wave (CDW) state is the ground state in various inorganic and organic materials with a chainlike structure, giving rise to remarkable electrical properties [2,3]. A particularly interesting feature of the CDW is its collective transport mode, somewhat similar to superconductivity [4]. Under an applied electric field, CDWs slide along the crystal, giving rise to a strongly nonlinear conductivity. Since even a small amount of disorder pins the CDWs, sliding occurs only when the applied electric field exceeds a certain threshold.In metallic and superconducting devices, reduction of sizes has revealed a variety of new mesoscopic phenomena. For CDW conductors, the mesoscopic regime has only been studied for small transverse dimensions [5][6][7] because samples of (sub)micron sizes in the chain direction could not be fabricated in a controlled way. Consequently, many aspects of microscopic CDW dynamics are still unknown. Nevertheless, some early studies on a micronscale revealed interesting mesoscopic features related to the CDW phase distribution [8,9]. More recently, artificial submicron CDW devices have been fabricated [10,11].In this paper, we present current-voltage (IV ) characteristics recorded on high-quality NbSe 3 and TaS 3 crystals with probe spacings in the submicron range (see the inset of Fig. 1). On these short length scales, IV curves vary strongly from segment to segment. For some segments the absolute resistance becomes negative, indicating that the moving CDW pumps single-particle carriers in a direction opposite to that of the rest of the sample. Our results show that the micron scale is the typical length scale for this new phenomenon in CDW dynamics.Experiments were carried out on single NbSe 3 and o-TaS 3 crystals with cross sections of 0.2 to 1 mm 2 . Both materials have a very anisotropic, chainlike structure [2]. NbSe 3 exhibits CDW transitions at T P1 145 K and T P2 59 K. At low temperatures a small portion of the conduction electrons remains uncondensed, providing a metallic single-particle channel. In contrast, in o-TaS 3 all electrons condense into the CDW state. As a result, the linear resistance shows semiconducting behavior below the transition temperature of 220 K.A common technique to contact small CDW whiskers consists of putting the crystals on top of metal probes that are evapor...

MAPPER Lithography is developing a maskless lithography technology based on massively-parallel electron-beam writing with high speed optical data transport for switching the electron beams. In this way optical columns can be made with a throughput of 10-20 wafers per hour. By clustering several of these systems together high throughputs can be realized in a small footprint. This enables a highly cost-competitive alternative to double patterning and EUV alternatives [1].In 2009 MAPPER shipped two systems one to TSMC and one to CEA-Leti. Both systems will be used to verify the applicability of MAPPER's technology for CMOS manufacturing.This paper presents a status update on the development of the MAPPER system over the past year. First an overview will be presented how to scale the current system to a 10 wph machine which can consequently be used in a cluster configuration to enable 100 wph throughputs.Then the results of today's (pre-) alpha systems with 300 mm wafer capability are presented from the machines at MAPPER, TSMC and CEA-Leti.

We have fabricated longitudinal nanoconstrictions in the charge-density wave conductor (CDW) NbSe 3 using a focused ion beam and using a mechanically controlled break-junction technique. Conductance peaks are observed below the T P1 145 K and T P2 59 K CDW transitions, which correspond closely with previous values of the full CDW gaps 2 1 and 2 2 obtained from photoemission. These results can be explained by assuming CDW-CDW tunneling in the presence of an energy gap corrugation 2 comparable to 2 , which eliminates expected peaks at j 1 2 j. The nanometer length scales our experiments imply indicate that an alternative explanation based on tunneling through back-to-back CDW-normal-conductor junctions is unlikely. DOI: 10.1103/PhysRevLett.96.096402 PACS numbers: 71.45.Lr, 73.23.ÿb, 73.40.Gk, 74.50.+r Charge-density wave (CDW) conduction remains of major interest despite its experimental discovery nearly 30 years ago. Much of the existing work has focused on transport properties of as-grown single crystals [1]. More recently, micro-and nanofabrication methods for CDW materials has allowed the study of mesoscopic CDW physics [2 -4]. Structures for tunneling spectroscopy are of particular interest because of the unusual gap structure with large one-dimensional fluctuation effects expected in these highly anisotropic materials, and because of predictions of unusual midgap excitations of the collective mode [5]. Tunneling studies in fully gapped CDW conductors like the ''blue bronze'' K 0:3 MoO 3 suffer from band-bending effects at the interface akin to semiconductor-insulatormetal junctions. These effects are absent in the partially gapped CDW conductor NbSe 3 , which remains metallic down to 4.2 K.Tunneling perpendicular to the direction b of the quasione-dimensional chains, along which the CDW wave vector lies, has been studied in ribbonlike whiskers of NbSe 3 by scanning tunneling microscopy (STM) [6], by tunneling through Pb contacts evaporated over the native oxide on the b-c plane [7,8], and by tunneling through a gold wire or a NbSe 3 crystal that is laid across another NbSe 3 crystal, forming junctions in the a-b or b-c planes [9,10]. Peaks in the T 4:2 K differential conductance at 35 and 101 mV [6], 35 mV [7], 36 mV and 90 mV [9], and 37 mV and 100 mV [10] from metal-NbSe 3 junctions correspond well with the CDW gaps 1 110 mV and 2 45 mV for NbSe 3 's T P1 145 K and T P2 59 K CDWs as determined by angle-resolved photo emission (ARPES) [11]. Crossed NbSe 3 -NbSe 3 crystals [9] yield peak voltages of 60 mV and 142 mV, and interlayer tunneling in microfabricated NbSe 3 mesas yields peaks at 50 mV and 120 mV [3]. A single in-chain tunneling study [2] using a gold ribbon mechanically positioned near the end of a NbSe 3 crystal gave a peak at 100 mV for the T P1 CDW.Here we demonstrate that a small constriction in a NbSe 3 single crystal, produced by dry etching with a Ga focused ion beam (FIB), shows conductance peaks at 105 mV and 190 mV corresponding to 2 1 and 2 2 , as illustrated in Fig. 1. We reproduce ...