Ac-dc interference, complete mode locking, and origin of coherent oscillations in sliding charge-density-wave systems

R. E. Thorne, J. S. Hubacek, W. G. Lyons, J. W. Lyding, J. R. Tucker

Research output: Contribution to journalArticle

Abstract

We present the results of a detailed experimental study of ac-dc interference phenomena in charge-density-wave (CDW) transport. The dc I-V characteristic of high-quality NbSe3 crystals, measured in the presence of an applied ac voltage, exhibits a remarkable array of Shapiro steps, including at least 150 subharmonic steps between the dc threshold and the 1/1 harmonic step. The harmonic and low-order subharmonic steps mode lock completely for ac frequencies between 100 kHz and 300 MHz and for ac amplitudes from a fraction of the dc threshold voltage VT to 75VT. The form and magnitude of the Bessel-like oscillations of the harmonic step widths with ac amplitude are independent of applied frequency at frequencies above 20 MHz, demonstrating conclusively that periodic CDW pinning by impurities does not vanish at high fields and frequencies. Surprisingly, even though CDWs are randomly pinned many-degree-of-freedom systems, single-coordinate models reproduce nearly all qualitative features of the Shapiro steps. A comparison between our interference measurements and our earlier coherent oscillation (narrow-band noise) measurements yields strong evidence that both effects are of bulk origin. We also have observed mode locking in the frequency domain by measuring the coherent oscillation spectrum in the presence of an applied ac voltage. When mode locking occurs, the spectral width of the fundamental peak collapses dramatically, indicating that the CDWs motion becomes almost perfectly periodic with no fluctuations. However, the amplitude of the fundamental does not change, suggesting that phase correlations are not dramatically enhanced. A detailed understanding of these results should yield important insights into the dynamics of charge-density waves and of other many-degree-of-freedom systems.

Original languageEnglish (US)
Pages (from-to)10055-10067
Number of pages13
JournalPhysical Review B
Volume37
Issue number17
DOIs
StatePublished - Jan 1 1988

Fingerprint

locking
sliding
interference
oscillations
harmonics
degrees of freedom
electric potential
noise measurement
threshold voltage
narrowband
impurities
thresholds
crystals

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Ac-dc interference, complete mode locking, and origin of coherent oscillations in sliding charge-density-wave systems. / Thorne, R. E.; Hubacek, J. S.; Lyons, W. G.; Lyding, J. W.; Tucker, J. R.

In: Physical Review B, Vol. 37, No. 17, 01.01.1988, p. 10055-10067.

Research output: Contribution to journalArticle

Thorne, R. E. ; Hubacek, J. S. ; Lyons, W. G. ; Lyding, J. W. ; Tucker, J. R. / Ac-dc interference, complete mode locking, and origin of coherent oscillations in sliding charge-density-wave systems. In: Physical Review B. 1988 ; Vol. 37, No. 17. pp. 10055-10067.
@article{7918fc4555ec495cb0642032de307b81,
title = "Ac-dc interference, complete mode locking, and origin of coherent oscillations in sliding charge-density-wave systems",
abstract = "We present the results of a detailed experimental study of ac-dc interference phenomena in charge-density-wave (CDW) transport. The dc I-V characteristic of high-quality NbSe3 crystals, measured in the presence of an applied ac voltage, exhibits a remarkable array of Shapiro steps, including at least 150 subharmonic steps between the dc threshold and the 1/1 harmonic step. The harmonic and low-order subharmonic steps mode lock completely for ac frequencies between 100 kHz and 300 MHz and for ac amplitudes from a fraction of the dc threshold voltage VT to 75VT. The form and magnitude of the Bessel-like oscillations of the harmonic step widths with ac amplitude are independent of applied frequency at frequencies above 20 MHz, demonstrating conclusively that periodic CDW pinning by impurities does not vanish at high fields and frequencies. Surprisingly, even though CDWs are randomly pinned many-degree-of-freedom systems, single-coordinate models reproduce nearly all qualitative features of the Shapiro steps. A comparison between our interference measurements and our earlier coherent oscillation (narrow-band noise) measurements yields strong evidence that both effects are of bulk origin. We also have observed mode locking in the frequency domain by measuring the coherent oscillation spectrum in the presence of an applied ac voltage. When mode locking occurs, the spectral width of the fundamental peak collapses dramatically, indicating that the CDWs motion becomes almost perfectly periodic with no fluctuations. However, the amplitude of the fundamental does not change, suggesting that phase correlations are not dramatically enhanced. A detailed understanding of these results should yield important insights into the dynamics of charge-density waves and of other many-degree-of-freedom systems.",
author = "Thorne, {R. E.} and Hubacek, {J. S.} and Lyons, {W. G.} and Lyding, {J. W.} and Tucker, {J. R.}",
year = "1988",
month = "1",
day = "1",
doi = "10.1103/PhysRevB.37.10055",
language = "English (US)",
volume = "37",
pages = "10055--10067",
journal = "Physical Review B",
issn = "0163-1829",
number = "17",

}

TY - JOUR

T1 - Ac-dc interference, complete mode locking, and origin of coherent oscillations in sliding charge-density-wave systems

AU - Thorne, R. E.

AU - Hubacek, J. S.

AU - Lyons, W. G.

AU - Lyding, J. W.

AU - Tucker, J. R.

PY - 1988/1/1

Y1 - 1988/1/1

N2 - We present the results of a detailed experimental study of ac-dc interference phenomena in charge-density-wave (CDW) transport. The dc I-V characteristic of high-quality NbSe3 crystals, measured in the presence of an applied ac voltage, exhibits a remarkable array of Shapiro steps, including at least 150 subharmonic steps between the dc threshold and the 1/1 harmonic step. The harmonic and low-order subharmonic steps mode lock completely for ac frequencies between 100 kHz and 300 MHz and for ac amplitudes from a fraction of the dc threshold voltage VT to 75VT. The form and magnitude of the Bessel-like oscillations of the harmonic step widths with ac amplitude are independent of applied frequency at frequencies above 20 MHz, demonstrating conclusively that periodic CDW pinning by impurities does not vanish at high fields and frequencies. Surprisingly, even though CDWs are randomly pinned many-degree-of-freedom systems, single-coordinate models reproduce nearly all qualitative features of the Shapiro steps. A comparison between our interference measurements and our earlier coherent oscillation (narrow-band noise) measurements yields strong evidence that both effects are of bulk origin. We also have observed mode locking in the frequency domain by measuring the coherent oscillation spectrum in the presence of an applied ac voltage. When mode locking occurs, the spectral width of the fundamental peak collapses dramatically, indicating that the CDWs motion becomes almost perfectly periodic with no fluctuations. However, the amplitude of the fundamental does not change, suggesting that phase correlations are not dramatically enhanced. A detailed understanding of these results should yield important insights into the dynamics of charge-density waves and of other many-degree-of-freedom systems.

AB - We present the results of a detailed experimental study of ac-dc interference phenomena in charge-density-wave (CDW) transport. The dc I-V characteristic of high-quality NbSe3 crystals, measured in the presence of an applied ac voltage, exhibits a remarkable array of Shapiro steps, including at least 150 subharmonic steps between the dc threshold and the 1/1 harmonic step. The harmonic and low-order subharmonic steps mode lock completely for ac frequencies between 100 kHz and 300 MHz and for ac amplitudes from a fraction of the dc threshold voltage VT to 75VT. The form and magnitude of the Bessel-like oscillations of the harmonic step widths with ac amplitude are independent of applied frequency at frequencies above 20 MHz, demonstrating conclusively that periodic CDW pinning by impurities does not vanish at high fields and frequencies. Surprisingly, even though CDWs are randomly pinned many-degree-of-freedom systems, single-coordinate models reproduce nearly all qualitative features of the Shapiro steps. A comparison between our interference measurements and our earlier coherent oscillation (narrow-band noise) measurements yields strong evidence that both effects are of bulk origin. We also have observed mode locking in the frequency domain by measuring the coherent oscillation spectrum in the presence of an applied ac voltage. When mode locking occurs, the spectral width of the fundamental peak collapses dramatically, indicating that the CDWs motion becomes almost perfectly periodic with no fluctuations. However, the amplitude of the fundamental does not change, suggesting that phase correlations are not dramatically enhanced. A detailed understanding of these results should yield important insights into the dynamics of charge-density waves and of other many-degree-of-freedom systems.

UR - http://www.scopus.com/inward/record.url?scp=0004814584&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0004814584&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.37.10055

DO - 10.1103/PhysRevB.37.10055

M3 - Article

AN - SCOPUS:0004814584

VL - 37

SP - 10055

EP - 10067

JO - Physical Review B

JF - Physical Review B

SN - 0163-1829

IS - 17

ER -