Low-frequency electronic noise in charge-density-wave van der Waals materials has been an important characteristic, providing information about the material quality, phase transitions, and collective current transport. However, the noise sources and mechanisms have not been completely understood, particularly for the materials with a non-fully gapped Fermi surface where the electrical current includes components from individual electrons and the sliding charge-density wave. We investigated noise in nanowires of quasi-one-dimensional NbSe3, focusing on a temperature range near the Pearls transition TP1 ∼ 145 K. The data analysis allowed us to separate the noise produced by the individual conduction electrons and the quantum condensate of the charge density waves before and after the onset of sliding. The noise as a function of temperature and electric bias reveals several intriguing peaks. We explained the observed features by the depinning threshold field, the creep and sliding of the charge density waves, and the possible existence of the hidden phases. It was found that the charge density wave condensate is particularly noisy at the moment of depinning. The noise of the collective current reduces with the increasing bias voltage in contrast to the noise of the individual electrons. Our results shed light on the behavior of the charge density wave quantum condensate and demonstrate the potential of noise spectroscopy for investigating the properties of low-dimensional quantum materials.

1.
A. A.
Balandin
,
F.
Kargar
,
T. T.
Salguero
, and
R. K.
Lake
, “
One-dimensional van der Waals quantum materials
,”
Mater. Today
55
,
74
91
(
2022
).
2.
Y.
Hu
,
W.
Zheng
,
S.
Fan
,
J.
Zhang
, and
X.
Liu
, “
Noble-transition-metal dichalcogenides-emerging two-dimensional materials for sensor applications
,”
Appl. Phys. Rev
10
(
3
),
031306
(
2023
).
3.
P.
Chava
,
Z.
Fekri
,
Y.
Vekariya
,
T.
Mikolajick
, and
A.
Erbe
, “
Band-to-band tunneling switches based on two-dimensional van der Waals heterojunctions
,”
Appl. Phys. Rev
10
(
1
),
011318
(
2023
).
4.
P. F.
Ferrari
,
S. P.
Kim
, and
A. M.
van der Zande
, “
Nanoelectromechanical systems from two-dimensional materials
,”
Appl. Phys. Rev
10
(
3
),
031302
(
2023
).
5.
J. O.
Brown
,
M.
Taheri
,
F.
Kargar
,
R.
Salgado
,
T.
Geremew
,
S.
Rumyantsev
,
R. K.
Lake
, and
A. A.
Balandin
, “
Current fluctuations and domain depinning in quasi-two-dimensional charge-density-wave 1T-TaS2 thin films
,”
Appl. Phys. Rev
10
(
4
),
041401
(
2023
).
6.
Z.
Barani
,
T.
Geremew
,
M.
Stokey
,
N.
Sesing
,
M.
Taheri
,
M. J.
Hilfiker
,
F.
Kargar
,
M.
Schubert
,
T. T.
Salguero
, and
A. A.
Balandin
, “
Quantum composites with charge-density-wave fillers
,”
Adv. Mater
35
(
19
),
2209708
(
2023
).
7.
Z. E.
Nataj
,
Y.
Xu
,
D.
Wright
,
J. O.
Brown
,
J.
Garg
,
X.
Chen
,
F.
Kargar
, and
A. A.
Balandin
, “
Cryogenic characteristics of graphene composites–evolution from thermal conductors to thermal insulators
,”
Nat. Commun.
14
(
1
),
3190
(
2023
).
8.
G.
Grüner
and
A.
Zettl
, “
Charge density wave conduction: A novel collective transport phenomenon in solids
,”
Phys. Rep.
119
(
3
),
117
232
(
1985
).
9.
G.
Grüner
, “
The dynamics of charge-density waves
,”
Rev. Mod. Phys.
60
(
4
),
1129
(
1988
).
10.
A.
Zettl
and
G.
Grüner
, “
Observation of Shapiro steps in the charge-density-wave state of NbSe3
,”
Solid State Commun.
46
(
7
),
501
504
(
1983
).
11.
J. C.
Gill
and
H. H.
Wills
, “
Charge-density wave transport
,”
Contemp. Phys.
27
(
1
),
37
59
(
1986
).
12.
A. A.
Balandin
,
S. V.
Zaitsev-Zotov
, and
G.
Grüner
, “
Charge-density-wave quantum materials and devices—New developments and future prospects
,”
Appl. Phys. Lett.
119
(
17
),
170401
(
2021
).
13.
G.
Liu
,
B.
Debnath
,
T. R.
Pope
,
T. T.
Salguero
,
R. K.
Lake
, and
A. A.
Balandin
, “
A charge-density-wave oscillator based on an integrated tantalum disulfide–boron nitride–graphene device operating at room temperature
,”
Nat. Nanotechnol.
11
(
10
),
845
850
(
2016
).
14.
X.
Xi
,
L.
Zhao
,
Z.
Wang
,
H.
Berger
,
L.
Forró
,
J.
Shan
, and
K. F.
Mak
, “
Strongly enhanced charge-density-wave order in monolayer NbSe2
,”
Nat. Nanotechnol.
10
(
9
),
765
769
(
2015
).
15.
C. W.
Chen
,
J.
Choe
, and
E.
Morosan
, “
Charge density waves in strongly correlated electron systems
,”
Rep. Prog. Phys.
79
(
8
),
084505
(
2016
).
16.
I. V.
Krive
and
A. S.
Rozhavsky
, “
On the nature of threshold electric field in quasi-one-dimensional commensurate charge-density-waves
,”
Solid State Commun.
55
(
8
),
691
694
(
1985
).
17.
A. J.
Berlinsky
, “
One-dimensional metals and charge density wave effects in these materials
,”
Rep. Prog. Phys.
42
(
7
),
1243
(
1979
).
18.
Y.
Wang
,
I.
Petrides
,
G.
McNamara
,
M. M.
Hosen
,
S.
Lei
,
Y. C.
Wu
,
J. L.
Hart
,
H.
Lv
,
J.
Yan
,
D.
Xiao
,
J. J.
Cha
,
P.
Narang
,
L. M.
Schoop
, and
K. S.
Burch
, “
Axial Higgs mode detected by quantum pathway interference in RTe3
,”
Nature
606
(
7916
),
896
901
(
2022
).
19.
W.
Shi
,
B. J.
Wieder
,
H. L.
Meyerheim
,
Y.
Sun
,
Y.
Zhang
,
Y.
Li
,
L.
Shen
,
Y.
Qi
,
L.
Yang
,
J.
Jena
,
P.
Werner
,
K.
Koepernik
,
S.
Parkin
,
Y.
Chen
,
C.
Felser
,
B. A.
Bernevig
, and
Z.
Wang
, “
A charge-density-wave topological semimetal
,”
Nat. Phys.
17
(
3
),
381
387
(
2021
).
20.
J. W.
Park
,
G. Y.
Cho
,
J.
Lee
, and
H. W.
Yeom
, “
Emergent honeycomb network of topological excitations in correlated charge density wave
,”
Nat. Commun.
10
(
1
),
4038
(
2019
).
21.
J.
Gooth
,
B.
Bradlyn
,
S.
Honnali
,
C.
Schindler
,
N.
Kumar
,
J.
Noky
,
Y.
Qi
,
C.
Shekhar
,
Y.
Sun
,
Z.
Wang
,
B. A.
Bernevig
, and
C.
Felser
, “
Axionic charge-density wave in the Weyl semimetal (TaSe4)2I
,”
Nature
575
(
7782
),
315
319
(
2019
).
22.
H.
Yi
,
Z.
Huang
,
W.
Shi
,
L.
Min
,
R.
Wu
,
C. M.
Polley
,
R.
Zhang
,
Y. F.
Zhao
,
L. J.
Zhou
,
J.
Adell
,
X.
Gui
,
W.
Xie
,
M. H. W.
Chan
,
Z.
Mao
,
Z.
Wang
,
W.
Wu
, and
C. Z.
Chang
, “
Surface charge induced Dirac band splitting in a charge density wave material (TaSe4)2I
,”
Phys. Rev. Res.
3
(
1
),
013271
(
2021
).
23.
B.
Horovitz
and
J. A.
Krumhansl
, “
Solitons in the Peierls condensate: Phase solitons
,”
Phys. Rev. B
29
(
4
),
2109
(
1984
).
24.
E. B.
Lopes
,
M. J.
Matos
,
R. T.
Henriques
,
M.
Almeida
, and
J.
Dumas
, “
CDW dynamics in the quasi-one-dimensional molecular conductors (Per)2M(mnt)2, (M=Au and Pt)
,”
Synth. Met.
86
(
1–3
),
2163
2164
(
1997
).
25.
X.
Zhu
,
J.
Guo
,
J.
Zhang
, and
E. W.
Plummer
, “
Misconceptions associated with the origin of charge density waves
,”
Adv. Phys. X
2
(
3
),
622
640
(
2017
).
26.
J. H.
Miller
and
M. Y.
Suárez-Villagrán
, “
Quantum fluidic charge density wave transport
,”
Appl. Phys. Lett.
118
(
18
),
184002
(
2021
).
27.
R. E.
Thorne
, “
Charge‐density‐wave conductors
,”
Phys. Today
49
(
5
),
42
47
(
1996
).
28.
M. J.
Rice
,
A. R.
Bishop
,
J. A.
Krumhansl
, and
S. E.
Trullinger
, “
Weakly pinned Fröhlich charge-density-wave condensates: A new, nonlinear, current-carrying elementary excitation
,”
Phys. Rev. Lett.
36
(
8
),
432
(
1976
).
29.
L.
Pietronero
,
S.
Strässler
, and
G. A.
Toombs
, “
Theory of the conductivity of the pinned Fröhlich charge density wave
,”
Phys. Rev. B
12
(
11
),
5213
(
1975
).
30.
R. M.
Fleming
, “
Electric-field depinning of charge-density waves in NbSe3
,”
Phys. Rev. B
22
(
12
),
5606
(
1980
).
31.
H.
Salva
,
Z. Z.
Wang
,
P.
Monceau
,
J.
Richard
, and
M.
Renard
, “
Charge density wave depinning in TaS3
,”
Philos. Mag. B
49
(
4
),
385
426
(
1984
).
32.
G.
Gr¨ner
,
A.
Zettl
,
W. G.
Clark
, and
A. H.
Thompson
, “
Observation of narrow-band charge-density-wave noise in TaS3
,”
Phys. Rev. B
23
(
12
),
6813
(
1981
).
33.
S.
Bhattacharya
,
J. P.
Stokes
,
M. O.
Robbins
, and
R. A.
Klemm
, “
Origin of broadband noise in charge-density-wave conductors
,”
Phys. Rev. Lett.
54
(
22
),
2453
(
1985
).
34.
S.
Bhattacharya
,
J. P.
Stokes
,
M. J.
Higgins
, and
M. O.
Robbins
, “
Broadband-noise spectrum in sliding-charge-density-wave conductors
,”
Phys. Rev. B
40
(
8
),
5826
(
1989
).
35.
A.
Zettl
and
G.
Grüner
, “
Charge-density-wave transport in orthorhombic TaS3. III. Narrow-band “noise
”,”
Phys. Rev. B
28
(
4
),
2091
(
1983
).
36.
I.
Bloom
,
A. C.
Marley
, and
M. B.
Weissman
, “
Correlation between broad-band noise and frequency fluctuations of narrow-band noise in the charge-density wave in NbSe3
,”
Phys. Rev. B
50
(
16
),
12218
(
1994
).
37.
S.
Onishi
,
M.
Jamei
, and
A.
Zettl
, “
Narrowband noise study of sliding charge density waves in NbSe3 nanoribbons
,”
New J. Phys.
19
(
2
),
023001
(
2017
).
38.
M. F.
Hundley
and
A.
Zettl
, “
Noise and ac-dc interference phenomena in the charge-density-wave conductor K0.3MoO3
,”
Phys. Rev. B
39
(
5
),
3026
(
1989
).
39.
G.
Liu
,
S.
Rumyantsev
,
M. A.
Bloodgood
,
T. T.
Salguero
, and
A. A.
Balandin
, “
Low-frequency current fluctuations and sliding of the charge density waves in two-dimensional materials
,”
Nano Lett.
18
(
6
),
3630
3636
(
2018
).
40.
A. K.
Geremew
,
S.
Rumyantsev
,
F.
Kargar
,
B.
Debnath
,
A.
Nosek
,
M. A.
Bloodgood
,
M.
Bockrath
,
T. T.
Salguero
,
R. K.
Lake
, and
A. A.
Balandin
, “
Bias-voltage driven switching of the charge-density-wave and normal metallic phases in 1T-TaS2 thin-film devices
,”
ACS Nano
13
(
6
),
7231
7240
(
2019
).
41.
I.
Bloom
,
A. C.
Marley
, and
M. B.
Weissman
, “
Discrete fluctuators and broadband noise in the charge-density wave in NbSe3
,”
Phys. Rev. B
50
(
8
),
5081
(
1994
).
42.
A. K.
Geremew
,
F.
Kargar
,
E. X.
Zhang
,
S. E.
Zhao
,
E.
Aytan
,
M. A.
Bloodgood
,
T. T.
Salguero
,
S.
Rumyantsev
,
A.
Fedoseyev
,
D. M.
Fleetwood
, and
A. A.
Balandin
, “
Proton-irradiation-immune electronics implemented with two-dimensional charge-density-wave devices
,”
Nanoscale
11
(
17
),
8380
8386
(
2019
).
43.
S. G.
Zybtsev
,
V. Y.
Pokrovskii
,
V. F.
Nasretdinova
, and
S. V.
Zaitsev-Zotov
, “
Growth, crystal structure and transport properties of quasi one-dimensional conductors NbS3
,”
Physica B
407
(
11
),
1696
1699
(
2012
).
44.
M.
Taheri
,
N.
Sesing
,
T. T.
Salguero
, and
A. A.
Balandin
, “
Electric-field modulation of the charge-density-wave quantum condensate in h-BN/NbS3 quasi-2D/1D heterostructure devices
,”
Appl. Phys. Lett.
123
(
23
),
233101
(
2023
).
45.
S.
Ghosh
,
F.
Kargar
,
N. R.
Sesing
,
Z.
Barani
,
T. T.
Salguero
,
D.
Yan
,
S.
Rumyantsev
, and
A. A.
Balandin
, “
Low-frequency current fluctuations in quasi-1D (TaSe4)2I Weyl semimetal nanoribbons
,”
Adv. Electron. Mater.
9
(
2
),
2200860
(
2023
).
46.
P.
Monceau
, “
Transport properties of NbSe3
,”
Physica B+C
109–110
(
C
),
1890
1900
(
1982
).
47.
J.
McCarten
,
D. A.
DiCarlo
,
M. P.
Maher
,
T. L.
Adelman
, and
R. E.
Thorne
, “
C Charge-density-wave pinning and finite-size effects in NbSe3
,”
Phys. Rev. B
46
(
8
),
4456
(
1992
).
48.
J.
Richard
,
P.
Monceau
,
M.
Papoular
, and
M.
Renard
, “
f noise in NbSe3
,”
J. Phys. C
15
(
35
),
7157
(
1982
).
49.
M. S.
Sherwin
,
A.
Zettl
, and
R. P.
Hall
, “
Switching and charge-density-wave transport in NbSe3. III. Dynamical instabilities
,”
Phys. Rev. B
38
(
18
),
13028
(
1988
).
50.
M. P.
Maher
,
T. L.
Adelman
,
J.
McCarten
,
D. A.
Dicarlo
, and
R. E.
Thorne
, “
Size effects, phase slip, and the origin of f noise in NbSe3
,”
Phys. Rev. B
43
(
12
),
9968
(
1991
).
51.
H. T.
Hardner
,
A. C.
Marley
,
M. B.
Weissman
, and
R. E.
Thorne
, “
Charge-density-wave memory loss under ac bias in NbSe3
,”
Phys. Rev. B
46
(
15
),
9833
(
1992
).
52.
M.
Weger
,
G.
Grüner
, and
W. G.
Clark
, “
Charge density wave noise in NbSe3
,”
Solid State Commun.
35
(
3
),
243
247
(
1980
).
53.
P.
Dutta
and
P. M.
Horn
, “
Low-frequency fluctuations in solids: 1/f noise
,”
Rev. Mod. Phys.
53
(
3
),
497
(
1981
).
54.
A. A.
Balandin
,
Noise and Fluctuations Control in Electronic Devices
(
American Scientific Publishers
,
2002
).
55.
G.
Mihly
,
G.
Hutiray
, and
L.
Mihly
, “
Macroscopic coherence length of charge-density waves in orthorhombic TaS3
,”
Phys. Rev. B
28
(
8
),
4896
(
1983
).
56.
D.
Borodin
,
S. V.
Zaitsev-Zotov
, and
F. Y.
Nad
, “
Coherence of a charge density wave and phase slip in small samples of a quasi-one-dimensional conductor TaS3
,”
Sov. Phys. JETP
66
(
4
),
793
(
1987
).
57.
A.
Zettl
and
G.
Grüner
, “
Phase coherence in the current-carrying charge-density-wave state: Ac-dc coupling experiments in NbSe3
,”
Phys. Rev. B
29
(
2
),
755
(
1984
).
58.
E.
Sweetland
,
C. Y.
Tsai
,
B. A.
Wintner
,
J. D.
Brock
, and
R. E.
Thorne
, “
Measurement of the charge-density-wave correlation length in NbSe3 by high-resolution x-ray scattering
,”
Phys. Rev. Lett.
65
(
25
),
3165
(
1990
).
59.
H.
Chen
,
Z.
Ma
,
Y.
Shao
,
Z. U.
Rehman
,
K.
Zhang
,
Q.
He
, and
L.
Song
, “
Angle-/temperature-dependence of Raman scattering in layered NbSe3 crystal
,”
AIP Adv.
7
(
9
),
095316
(
2017
).
60.
S.
Ghosh
,
F.
Kargar
,
A.
Mohammadzadeh
,
S.
Rumyantsev
,
A. A.
Balandin
,
S.
Ghosh
,
F.
Kargar
,
A.
Mohammadzadeh
,
A. A.
Balandin
, and
S.
Rumyantsev
, “
Low-frequency electronic noise in quasi-2D van der Waals antiferromagnetic semiconductor FePS3—Signatures of phase transitions
,”
Adv. Electron. Mater.
7
(
12
),
2100408
(
2021
).
61.
N. P.
Ong
and
P.
Monceau
, “
Anomalous transport properties of a linear-chain metal: NbSe3
,”
Phys. Rev. B
16
(
8
),
3443
(
1977
).
62.
J.
Chaussy
,
P.
Haen
,
J. C.
Lasjaunias
,
P.
Monceau
,
G.
Waysand
,
A.
Waintal
,
A.
Meerschaut
,
P.
Molinié
, and
J.
Rouxel
, “
Phase transitions in NbSe3
,”
Solid State Commun.
20
(
8
),
759
763
(
1976
).
63.
P.
Monçeau
,
N. P.
Ong
,
A. M.
Portis
,
A.
Meerschaut
, and
J.
Rouxel
, “
Electric field breakdown of charge-density-wave—Induced anomalies in NbSe3
,”
Phys. Rev. Lett.
37
(
10
),
602
(
1976
).
64.
R. M.
Fleming
and
C. C.
Grimes
, “
Sliding-mode conductivity in NbSe3: Observation of a threshold electric field and conduction noise
,”
Phys. Rev. Lett.
42
(
21
),
1423
(
1979
).
65.
T. L.
Adelman
,
S. V.
Zaitsev-Zotov
, and
R. E.
Thorne
, “
Field-effect modulation of charge-density-wave transport in NbSe3 and TaS3
,”
Phys. Rev. Lett.
74
(
26
),
5264
(
1995
).
66.
A. V.
Frolov
,
A. P.
Orlov
,
F.
Gay
,
A. A.
Sinchenko
, and
P.
Monceau
, “
Distinctive features of the charge density wave collective motion driven by Hall electric field in NbSe3
,”
Appl. Phys. Lett.
118
(
21
),
213102
(
2021
).
67.
S.
Van Smaalen
,
J. L.
De Boer
,
A.
Meetsma
,
H.
Graafsma
,
H. S.
Sheu
,
A.
Darovskikh
,
P.
Coppens
, and
F.
Levy
, “
Determination of the structural distortions corresponding to the to the q1- and q2-type modulations in niobium triselenide NbSe3
,”
Phys. Rev. B
45
(
6
),
3103
(
1992
).
68.
S.
Ghosh
,
D. H.
Mudiyanselage
,
F.
Kargar
,
Y.
Zhao
,
H.
Fu
, and
A. A.
Balandin
, “
Temperature dependence of low-frequency noise characteristics of NiOx/β-Ga2O3 p–n heterojunction diodes
,”
Adv. Electron. Mater.
10
(
2
),
2300501
(
2024
).
69.
S.
Ghosh
,
D. H.
Mudiyanselage
,
S.
Rumyantsev
,
Y.
Zhao
,
H.
Fu
,
S.
Goodnick
,
R.
Nemanich
, and
A. A.
Balandin
, “
Low-frequency noise in β-(AlxGa1−x)2O3 Schottky barrier diodes
,”
Appl. Phys. Lett.
122
(
21
),
212109
(
2023
).
70.
S.
Ghosh
,
K.
Fu
,
F.
Kargar
,
S.
Rumyantsev
,
Y.
Zhao
, and
A. A.
Balandin
, “
Low-frequency noise characteristics of GaN vertical PIN diodes—Effects of design, current, and temperature
,”
Appl. Phys. Lett.
119
(
24
),
243505
(
2021
).
71.
S.
Ghosh
,
H.
Surdi
,
F.
Kargar
,
F. A.
Koeck
,
S.
Rumyantsev
,
S.
Goodnick
,
R. J.
Nemanich
, and
A. A.
Balandin
, “
Excess noise in high-current diamond diodes
,”
Appl. Phys. Lett.
120
(
6
),
62103
(
2022
).
72.
A. A.
Balandin
, “
Low-frequency 1/f noise in graphene devices
,”
Nat. Nanotechnol.
8
(
8
),
549
555
(
2013
).
73.
S. V.
Zaitsev-Zotov
, “
Finite-size effects in quasi-one-dimensional conductors with a charge-density wave
,”
Phys.-Usp.
47
(
6
),
533
554
(
2004
).
74.
H.
Ichikawa
,
S.
Nozawa
,
T.
Sato
,
A.
Tomita
,
K.
Ichiyanagi
,
M.
Chollet
,
L.
Guerin
,
N.
Dean
,
A.
Cavalleri
,
S. I.
Adachi
,
T. H.
Arima
,
H.
Sawa
,
Y.
Ogimoto
,
M.
Nakamura
,
R.
Tamaki
,
K.
Miyano
, and
S. Y.
Koshihara
, “
Transient photoinduced ‘hidden’ phase in a manganite
,”
Nat. Mater.
10
(
2
),
101
105
(
2011
).
75.
I.
Vaskivskyi
,
I. A.
Mihailovic
,
S.
Brazovskii
,
J.
Gospodaric
,
T.
Mertelj
,
D.
Svetin
,
P.
Sutar
, and
D.
Mihailovic
, “
Fast electronic resistance switching involving hidden charge density wave states
,”
Nat. Commun.
7
(
1
),
11442
(
2016
).
76.
R.
Salgado
,
A.
Mohammadzadeh
,
F.
Kargar
,
A.
Geremew
,
C. Y.
Huang
,
M. A.
Bloodgood
,
S.
Rumyantsev
,
T. T.
Salguero
, and
A. A.
Balandin
, “
Low-frequency noise spectroscopy of charge-density-wave phase transitions in vertical quasi-2D 1T-TaS2 devices
,”
Appl. Phys. Express
12
(
3
),
037001
(
2019
).
77.
E.
Pinsolle
,
N.
Kirova
,
V. L. R.
Jacques
,
A. A.
Sinchenko
, and
D. L.
Bolloc'H
, “
Creep, flow, and phase slippage regimes: An extensive view of the sliding charge-density wave revealed by coherent x-ray diffraction
,”
Phys. Rev. Lett.
109
(
25
),
256402
(
2012
).
78.
J. C.
Gill
, “
Thermally initiated phase-slip in the motion and relaxation of charge-density waves in niobium triselenide
,”
J. Phys. C
19
(
33
),
6589
(
1986
).
79.
R. P.
Hall
,
M. F.
Hundley
, and
A.
Zettl
, “
Switching and charge-density-wave transport in NbSe3. I. dc characteristics
,”
Phys. Rev. B
38
(
18
),
13002
(
1988
).
80.
A.
Mohammadzadeh
,
A.
Rehman
,
F.
Kargar
,
S.
Rumyantsev
,
J. M.
Smulko
,
W.
Knap
,
R. K.
Lake
, and
A. A.
Balandin
, “
Room temperature depinning of the charge-density waves in quasi-two-dimensional 1T-TaS2 devices
,”
Appl. Phys. Lett.
118
(
22
),
223101
(
2021
).

Supplementary Material

You do not currently have access to this content.