Skip to main content
Home
Department Of Physics text logo
  • Research
    • Our research
    • Our research groups
    • Our research in action
    • Research funding support
    • Summer internships for undergraduates
  • Study
    • Undergraduates
    • Postgraduates
  • Engage
    • For alumni
    • For business
    • For schools
    • For the public
Menu
Magnetic skyrmions

Professor Thorsten Hesjedal FInstP

Professor of Condensed Matter Physics

Research theme

  • Quantum materials

Sub department

  • Condensed Matter Physics

Research groups

  • Thin film quantum materials
  • Oxford Quantum Institute
  • Magnetism for Intelligent Devices (MIND)
Thorsten.Hesjedal@physics.ox.ac.uk
Telephone: 01865 (2)72235
  • About
  • Publications

Surfing the SAW: Visualizing the oscillation of Au(111) surface atoms

Proceedings of the IEEE Ultrasonics Symposium 1 (1997) 511-514

Authors:

T Hesjedal, E Chilla, HJ Froehlich

Abstract:

In this paper we report the observation of surface acoustic waves using a scanning tunneling microscope (STM). As the STM's control electronics has a bandwidth limit in the kHz range, SAWs at typical frequencies of MHz to GHz cause a loss of contrast which can be clearly seen on an atomic scale. In order to access the amplitude and phase of a SAW, we introduced a heterodyning type STM, the scanning acoustic tunneling microscope (SATM). Contrary to the STM technique, the SATM measures snapshots of the state of oscillation. On the nanometer scale, two contributions to the phase and amplitude contrast are discussed. First, the SAWs phase delay gives a mainly linear dependence on the distance of the source. Second, the atomic oscillation trajectories within the SAW lead to a signal contribution that is made up of the shape of the oscillation trajectory and the local topography. On an atomic scale where the influence of the phase delay on the contrast can be neglected the oscillation trajectories of single surface atoms are studied. Finally, the atomically resolved phase and amplitude images are compared to simulated data.
More details
More details from the publisher

Towards the determination of elastic constants on a submicron scale using scanning acoustic force microscopy

Proceedings of the IEEE Ultrasonics Symposium 1 (1997) 549-552

Authors:

T Hesjedal, E Chilla, HJ Froehlich

Abstract:

This paper reports first steps towards the determination of elastic constants with submicron lateral resolution. The experimental phase velocity dispersion data were obtained on a micron scale using scanning acoustic force microscopy. The minimum of the corresponding error field is only weakly localized, thus giving a large error for the elastic constants. The localization can not be increased by using more of data points. In order to decrease the elastic constant's error, a Love mode is additionally regarded. However, the error field crossing is in this case not leading to a significant increase of the accuracy. We propose the inclusion of further surface guided modes.
More details
More details from the publisher

High resolution visualization of acoustic wave fields within surface acoustic wave devices

Applied Physics Letters 70:11 (1997) 1372-1374

Authors:

T Hesjedal, E Chilla, HJ Fröhlich

Abstract:

We present the submicron visualization of surface acoustic wave (SAW) fields within interdigital transducers (IDTs) obtained by a scanning acoustic force microscope. Utilizing the nonlinear force curve of the tip-to-surface interaction, a periodic deflection of the cantilever appears when the SAWs are excited intermittently. This deflection depends on the amplitude of the surface oscillation and was measured by lock-in technique. SAWs with operating frequencies above 600 MHz were detected. The influence of the mass loading on the local oscillation amplitude was studied for various layer thicknesses of the IDT electrodes. © 1997 American Institute of Physics.
More details from the publisher
More details

Nanoscale determination of phase velocity by scanning acoustic force microscopy

Physical Review B - Condensed Matter and Materials Physics 55:23 (1997) 15852-15855

Authors:

E Chilla, T Hesjedal, HJ Fröhlich

Abstract:

We measured the phase velocity of surface acoustic waves (SAWșs) with a scanning acoustic force microscope (SAFM) and achieved a maximum lateral resolution of 19.9 nm. The phase measurement of high-frequency waves with a slowly responding SAFM cantilever was perfomed by frequency mixing at its nonlinear force curve. For Au layers of different thicknesses the SAW dispersion was studied on a lateral scale of 200 nm and compared to calculated data. © 1997 The American Physical Society.
More details from the publisher
More details

Scanning acoustic force microscope investigations of surface acoustic waves

Surface and Interface Analysis 25:7-8 (1997) 569-572

Authors:

T Hesjedal, E Chilla, HJ Fröhlich

Abstract:

We report on the investigation of surface acoustic wave (SAW) fields by scanning acoustic force microscopy (SAFM), reaching submicron lateral resolution. The SAFM is based on a standard atomic force microscope and utilizes the non-linear force curve in the sense of a mechanical diode. The surface oscillation therefore leads to a shift of the cantilever's rest position. With SAFM we investigated SAW transducers operating at frequencies above 600 MHz. We measured the dynamic behaviour of the wave pattern within the transducers when sweeping the frequency and found a local influence of mass loading on the standing SAW amplitude. Furthermore, the first images of SAW diffraction and scattering are shown. © 1997 by John Wiley & Sons, Ltd.
More details from the publisher
More details

Pagination

  • First page First
  • Previous page Prev
  • …
  • Page 68
  • Page 69
  • Page 70
  • Page 71
  • Current page 72
  • Page 73
  • Page 74
  • Page 75
  • Page 76
  • …
  • Next page Next
  • Last page Last

Footer Menu

  • Contact us
  • Giving to the Dept of Physics
  • Work with us
  • Media

User account menu

  • Log in

Follow us

FIND US

Clarendon Laboratory,

Parks Road,

Oxford,

OX1 3PU

CONTACT US

Tel: +44(0)1865272200

University of Oxfrod logo Department Of Physics text logo
IOP Juno Champion logo Athena Swan Silver Award logo

© University of Oxford - Department of Physics

Cookies | Privacy policy | Accessibility statement

Built by: Versantus

  • Home
  • Research
  • Study
  • Engage
  • Our people
  • News & Comment
  • Events
  • Our facilities & services
  • About us
  • Current students
  • Staff intranet