Bulletin of the American Physical Society
APS March Meeting 2015
Volume 60, Number 1
Monday–Friday, March 2–6, 2015; San Antonio, Texas
Session L21: Focus Session: Advances in Scanned Probe Microscopy III: Novel Spectroscopic and Imaging Measurements |
Hide Abstracts |
Sponsoring Units: GIMS Chair: Jonathan Wyrick, National Institute of Standards and Technology Room: 201 |
Wednesday, March 4, 2015 8:00AM - 8:12AM |
L21.00001: Design and performance of a cryogenic scanning tunneling microscope in high magnetic field for 2D layered materials study Tien-Ming Chuang, Pei-Fang Chung, Syu-You Guan, Shan-An Yu, Che-An Liu, Chia-Sheng Hsu, Chih-Chuan Su, Raman Sankar, Fang-Cheng Chou We will describe the design and performance of a cryogenic scanning tunneling microscope (STM) system in a high magnetic field. A Pan-type STM is mounted on a homemade low vibration 4He pot refrigerator, which can be operated in continuous flow mode at T $\sim$ 1.6K and in a magnetic field of up to 9 Tesla. A cleavage device at T$=$4.2K stage is used to cleave the 2D layered materials before inserting into STM as well as functioning as the radiation shield. The liquid helium boil rate of 4.6 liters per day is achieved due to our careful design, which allows the measurement at base temperature up to 10 days. We will demonstrate its capability of measuring atomically registered energy resolved spectroscopic maps in both real space and momentum space by our recent results on Rashba BiTeI. [Preview Abstract] |
Wednesday, March 4, 2015 8:12AM - 8:24AM |
L21.00002: ABSTRACT WITHDRAWN |
Wednesday, March 4, 2015 8:24AM - 8:36AM |
L21.00003: Quantum Interference between Energy Absorption Processes of Molecular Exciton and Interface Plasmons on Luminescence Induced by Scanning Tunneling Microscopy Kuniyuki Miwa, Hiroshi Imada, Mamoru Sakaue, Hideaki Kasai, Yousoo Kim Luminescence induced by the tunneling current of a scanning tunneling microscope (STM) from molecule-covered metal surfaces is attributed to radiative decays of molecules and interface plasmons localized near the tip-substrate gap region. Since the dynamics of molecule and interface plasmons strongly influence each other, the interplay between these dynamics gives rise to peculiar phenomena originating from quantum many-body effects. In this study, we develop the effective model of the system and investigate the luminescence properties using the nonequilibrium Green's function method. The results show that, in addition to the dynamics of molecule, energy reabsorption by interface plasmons have a critical role in determining the luminescence spectral profile of interface plasmons. The additional peak structure arises owing to the interference between these energy absorption processes. Origin of prominent peak and dip structures observed in recent experiments are identified by the developed theory. The details of the interference effects on the luminescence properties will be discussed. [Preview Abstract] |
Wednesday, March 4, 2015 8:36AM - 8:48AM |
L21.00004: Image Distortions of Molecules in Atomic Force Microscopy with Carbon Monoxide Terminated Tips Nikolaj Moll, Leo Gross, Bruno Schuler, Alessandro Curioni, Gerhard Meyer Using functionalized tips, the atomic resolution of a single organic molecule can be achieved by atomic force microscopy (AFM) operating in the regime of short-ranged repulsive Pauli forces while the van-der-Waals and electrostatic interactions only add a diffuse attractive background\footnote{L. Gross, F. Mohn, N. Moll, P. Liljeroth, and G. Meyer, Science 325, 1110 (2009).}. The underlying mechanisms of image distortions with CO-terminated tips are identified and studied in detail\footnote{N. Moll, B. Schuler, S. Kawai, F. Xu, L. Peng, A. Orita, J. Otera, A. Curioni, M. Neu, J. Repp, G. Meyer, and L. Gross, Nano Lett. (2014).}. Parts of a molecule appear different in size, which primarily originates from the charge density. Further, tilting of the CO at the tip, induced by van der Waals forces, enlarges the apparent size of parts of the molecule by up to 50 \%. Moreover, the CO tilting in response to local Pauli repulsion causes a significant sharpening of the molecule bonds in AFM imaging. With these image distortions it is possible to distinguish different bond orders of individual carbon-carbon bonds in organic molecules by AFM. [Preview Abstract] |
Wednesday, March 4, 2015 8:48AM - 9:00AM |
L21.00005: Three-Dimensional Imaging of Complex Molecular Electronic States via Atomic Manipulation Reconstruction Eric Chatterjee, Dominik Rastawicki, Alex Contryman, Yan Sun, Dylan Reuter, Hari Manoharan We describe a method based on STM atomic manipulation for experimentally capturing the complete three-dimensional electronic structure of complex molecules. Using techniques we have recently developed for assembling molecular graphene and related materials, we vary specific site potentials, intersite hopping amplitudes, and Fermi energy in 2D nanostructures which when wrapped into a 3D container represent a new probe molecule. Here we present the design methods and analyses of a number of such molecules, focusing on those containing rotational symmetry. We show how various types of fullerenes, of interest due to their electronic and vibrational properties, can be unwrapped on a 2D surface, reprogrammed, and rewrapped to 3D. Examples of the unwrapping methods include cutting selected bonds in order to sever adjacent faces or sites. Analysis of the local density of states for 2D correspondents to fullerenes yields the presence of peaks at the highest occupied molecular orbital and lowest unoccupied molecular orbital, with an energy gap between these levels. The replication of these properties of fullerenes in 2D space serves as evidence of the significant potential of STM assembly and spectroscopy in studying the applicability of exotic 3D molecules in electronics. [Preview Abstract] |
Wednesday, March 4, 2015 9:00AM - 9:12AM |
L21.00006: Gauge Fields and Topological Confinement in Synthetic Nanomaterials Assembled via Atomic Manipulation Dominik Rastawicki, Eric Chatterjee, Yan Sun, Alex Contryman, Dylan Rueter, Hari Manoharan The assembly of molecular graphene and related nanostructures demonstrated that atomic manipulation can be used to build functional quantum nanomaterials site by site and bond by bond. This level of precise control lets one tune the potential of each site, the hopping strength of each bond, and---by adjusting lattice size---the Fermi energy and relative interaction strength inside and between sites. Here we present examples of new molecular materials assembled and characterized by STM/STS exploiting these techniques. We show that lattices with varying site potential across six sites of a unit cell show signatures of non-abelian gauge fields. We will contrast observed behavior with conventional abelian gauge fields built into the same structures. We will also show that boundaries between patterned mass domains can induce topological edge states and topological charge confinement. We will also discuss the engineering of flat bands into more complex materials, and show effects of the resulting quenching of kinetic energy. [Preview Abstract] |
Wednesday, March 4, 2015 9:12AM - 9:48AM |
L21.00007: Chiral Enhanced Phonon Excitations in Inelastic Electron Tunneling Spectroscopy of Graphene Invited Speaker: Fabian Donat Natterer In graphene, phonons are important agents for a wide range of phenomena; they mediate relaxation rates for hot carriers, they lead to van-Hove singularities, and they induce a renormalization of the Fermi velocity due to electron-phonon coupling and many-body interactions [1]. The previous observations of phonons [2-4] by inelastic electron tunneling spectroscopy (IETS) have been expandable in terms of detail and resolution, due to weak signals and other spectral features which inhibit a clear distinction between phonons and miscellaneous excitations. We find that utilizing a back gated graphene device, where the graphene charge carrier density can be varied in magnitude and sign, allows all the critical point graphene phonons with large density of states to be sampled by IETS with the scanning tunneling microscope, and in good agreement with density functional calculations. In addition, a strong overtone excitation at 360 meV is observed. Quite surprisingly, we observe all the graphene excitations are resonantly enhanced when the charge carrier type is switched, indicating that this amplification occurs whenever the inelastic transition allows a change in the graphene chirality. The chiral enhancement is observed to follow a linear trend with energy and reaches almost an order of magnitude for the highest transition. Our averaging technique suppresses charge carrier dependent excitations, while it improves the signal for inelastic transitions. This approach can be employed as a guide in advanced studies that are relying on gate tunable graphene devices, such as for the detection of spin, vibrational, or rotational excitations in adsorbates.\\[4pt] [1] Basov et al. Rev. Mod. Phys. \textbf{86}, 959 (2014).\\[0pt] [2] Vitali et al. Phys. Rev. B \textbf{69}, 121414 (2004).\\[0pt] [3] Zhang et al. Nat. Phys \textbf{4}, 627 (2008).\\[0pt] [4] Li et al. Phys. Rev. Lett. \textbf{102}, 176804 (2009). [Preview Abstract] |
Wednesday, March 4, 2015 9:48AM - 10:00AM |
L21.00008: Probing the Hydrogen Bond Strength at Single Bond Limit Jing Guo, Jing-Tao L\"u, Ji Chen, Jinbo Peng, Xiangzhi Meng, Zhichang Wang, Xin-Zheng Li, Enge Wang, Ying Jiang Many extraordinary physical, chemical and biological properties of water are determined by hydrogen-bonding interaction between the water molecules. So far, the routine way to determine the hydrogen-bonding strength of water is probing the frequency shift of O-H stretching mode using various spectroscopic techniques, which all suffer from the difficulty of spectral assignment and the broadening of vibrational signals due to the lack of spatial resolution. In this talk, we show the ability to probe the hydrogen-bonding strength of interfacial water at single bond limit using resonantly enhanced inelastic electron tunneling spectroscopy (IETS) with a scanning tunneling microscope (STM). The conventional IET signals of water molecules are extremely weak and far beyond the experimental detection limit due to the negligible molecular density of states (DOS) around the Fermi level. This difficulty can be surmounted by turning on the tip-water coupling, which shifts and broadens the frontier molecular orbitals of water to the proximity of Fermi level, resulting in a resonantly enhanced IET process. [Preview Abstract] |
Wednesday, March 4, 2015 10:00AM - 10:12AM |
L21.00009: Mechanism of high-resolution STM, AFM and IETS-STM imaging with functionalized tips R. Temirov, P. Hapala, F.S. Tautz, P. Jelinek High-resolution AFM and STM with functionalized tips is well established [1,2], but a detailed understanding of the image mechanism is still missing. Moreover, recently this family of imaging techniques has been complemented by a method based on inelastic electron tunneling spectroscopy [3]. Here we present a comprehensive mechanical and transport simulation model [4,5] that explains essentially all image features in functionalized tip STM, AFM and IETS-STM. Important aspects of the mechanism are: (i) Images are dominantly determined by Pauli repulsion [6], (ii) in STM and IETS STM this force signal is transduced into an elastic [6,7] or inelastic [5] conductance signal, (iii) probe particle relaxation leads to image sharpening [4], (iv) the apparent imaging of hydrogen bonds can be explained by a relaxation effect [4], and (v) electrostatic forces may also influence the image contrast [5]. [1] Temirov et al., New J Phys 10, 053012 (2008) [2] Gross et al., Science 325, 1110 (2009) [3] Chiang, et al., Science 344, 885 (2014) [4] Hapala et al. Phys. Rev. B 90, 085421 (2014) [5] Hapala et al. Phys. Rev. Lett. 2014 in press [6] Weiss, et al. Phys. Rev. Lett. 105, 086103 (2010) [7] Kichin et al. Phys. Rev. B 87, 081408(R) (2013) [Preview Abstract] |
Wednesday, March 4, 2015 10:12AM - 10:24AM |
L21.00010: Elemental Fingerprinting of Materials with Sensitivity at the Atomic Limit Marvin Cummings, Nozomi Shirato, Heath Kersell, Yang Li, Benjamin Stripe, Daniel Rosenmann, Saw-Wai Hla, Volker Rose Variants of scanning probe microscopes have proven tremendously valuable for extracting detailed information about the nature of a sample's surface (atomic, electronic, magnetic), however it has proven difficult to yield chemical information utilizing scanning probe techniques alone. At Argonne National Laboratory's Advanced Photon Source, a new in-situ high-resolution microscopy technique, the synchrotron x-ray scanning tunneling microscope (SXSTM), utilizes x-rays as a chemical, electronic and magnetic probe and the nanofabricated tips of a scanning tunneling microscope as the chemical detector to take full advantage of the sub-nm spatial resolutions that STMs provide. Utilizing the new SXSTM technique, chemical fingerprinting of individual nickel clusters on a Cu(111) surface has been demonstrated with a 2 nm lateral resolution and a sensitivity confined to the first atomic surface layer. In addition, the photoionization cross-section from a single nm-scale Ni cluster has been successfully measured. SXSTM could prove to be a powerful new surface characterization technique, enabling exciting areas of opportunity and discovery in the chemical and materials sciences. [Preview Abstract] |
Wednesday, March 4, 2015 10:24AM - 10:36AM |
L21.00011: Direct elemental and magnetic contrast of magnetic thin films and nanoparticles measured by synchrotron X-ray scanning tunneling microscopy and spectroscopy Andrew DiLullo, N. Shirato, M. Cummings, H. Kersell, S.-W. Hla, V. Rose Synchrotron X-ray scanning tunneling microscopy (SX-STM) combines two of the most robust characterization instruments of materials science in a single setting and it can provide elemental fingerprinting of materials down to the atomic limits [1]. Here, we show that the SX-STM can also be useful for the magnetic measurements with elemental specificity by combining tunneling microscopy and spectroscopy with the X-ray magnetic circular dichroism (XMCD) technique. The experiments are performed in the Advanced Photon Source beam line 4-ID-C using a custom-built SX-STM system. During the experiment, the circularly polarized synchrotron light is projected onto iron nanoclusters adsorbed on a cobalt thin film on Cu(111) surface, and the resulting photo-current is collected by a nano-fabricated SX-STM tip. The photocurrent intensity clearly reveals majority and minority spin states when measured at L2 and L3 edges of the magnetic materials. We will also discuss the enormous potential of this nascent technique in characterizations of materials at atomic limits. \\[4pt] [1] N. Shirato, M. Cummings, H. Kersell, Y. Li, B. Stripe, D. Rosenmann, S.-W. Hla, and V. Rose. Elemental Fingerprinting of Materials with Sensitivity at the Atomic Limit. Nano Lett. 14, 6499--6504 (2014). [Preview Abstract] |
Wednesday, March 4, 2015 10:36AM - 10:48AM |
L21.00012: Schottky Barrier mapping of the W/Si diode using ballistic electron emission microscopy Christopher Durcan, Robert Balsano, Nicholas Pieniazek, Vincent LaBella The Schottky barrier of the W/Si(001) diode was investigated and spatially mapped at the nanoscale using ballistic electron emission microscopy (BEEM) and ballistic hole emission microscopy (BHEM). The miscibility of tungsten and silicon creates a thin silicide upon deposition with transmission electron microscopy (TEM) and Rutherford backscattering spectrometry (RBS) showing the changes in the silicide over several weeks. Using standard current voltage measurements there is no change in the charge transport across the diode during this time period. However, BEEM measurements do show dramatic changes to the transport of ballistic electrons over time with nanoscale resolution. Time dependent Schottky barrier maps are generated over a 1$\mu$m x 1$\mu$m area and provide valuable insight to the barrier height homogeneity, defect formation, and interfacial effects occurring in the diode. [Preview Abstract] |
Wednesday, March 4, 2015 10:48AM - 11:00AM |
L21.00013: Obtaining reliable friction data at the nanoscale by tuning AFM parameters Sung Hyun Kim, Suenne Kim Carefully devised experimental study of friction at the nanoscale in dry system is desired for proper mathematical modeling or for quantitative research. Experimentally, contact mode atomic force microscope (AFM) which is able to perform lateral force microscopy (LFM) can be used for acquiring frictional data. To obtain reliable LFM information, we have investigated the effect of scanning parameters, especially gain and scanning rate, on the LFM measurements. Depending on the parameters selected, the relative ratio of the friction force obtained from graphene to that of SiO2 varies greatly from about 1 to 0.1. We will discuss, here, firstly how to understand this behavior and secondly the parameter-optimization procedure for the LFM imaging, which is different from the height imaging, eventually to aid quantitative LFM studies. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700