Proximity Effect in Hybrid Superconducting/Organic molecule nano particle system
Yossi Paltiel Applied Physics Department Center for nano science and nano technology, HUJI, Israel
Oded Millo Nadav Katz
Quantum Nano Engineering Lab 10/23/2015 1 L a b Many thanks to
Our Group: Dr. Shira Yochelis, Eyal Cohen, Eran Katzir, Avner Neubauer, Guy Koplovitz, Oren Ben Dor, Ido Eisnberg, Ohad Westrich, Matan Galanty. Nir Sukenick, Chen Alpern; Amir Ziv, Aviya Perlman Illouz, Kuti Uliel
And
Grzegorz Jung Physics department , Ben Gurion University Beer Sheva Israel
Ron Naaman Department of Chemical Physics, Weizmann Institute, Rehovot 76100, Israel
Nadav Katz, Yaov Kalcheim, Oded Millo , Racah Institute of Physics, Hebrew University, Jerusalem 91904, Israel
Uri Banin Department of physical chemistry , Hebrew University, Jerusalem 91904, Israel
Financing:, ISF, ISF-BICORA, DARPA, MOD, Israel Taiwan, Magneton Capital Nature , FTA , Peter Brojde center, MOS, Volkswagen, Leverhulme Quantum Nano Engineering Lab 10/23/2015 2 L a b Molecular Electronics
Eleke Scheer break junctions
A. Aviram and M. Ratner, in Annals Our work on chiral induced spintronics of the New York Academy of Sciences (1998).
Quantum Nano Engineering Lab 10/23/2015 3 L a b Theory
Electron transmission through molecules and molecular interfaces Review by Abraham Nitzan
“Electron transmission through molecules and molecular interfaces has been a subject of intensive research due to recent interest in electron transfer phenomena underlying the operation of the scanning tunneling microscope (STM) on one hand, and in the transmission properties of molecular bridges between conducting leads on the other. In these processes the traditional molecular view of electron transfer between donor and acceptor species give rise to a novel view of the molecule as a current carrying conductor, and observables such as electron transfer rates and yields are replaced by the conductivities, or more generally by current-voltage relationships, in molecular junctions. Such investigations of electrical junctions, in which single molecules or small molecular assemblies operate as conductors constitutes a major part of what has become the active field of molecular electronics.
Quantum Nano Engineering Lab 10/23/2015 4 L a b Can molecules support proximity effect? Two transport channels in parallel of electrons and holes??? Or one channel near Fermi surface???
Quantum Nano Engineering Lab 10/23/2015 5 L a b Huge difference between molecule and SC gap
LUMO LUMO
Small SC gap µ Small SC gap
HOMO HOMO
Non trivial band alignment
Quantum Nano Engineering Lab 10/23/2015 6 L a b How would proximity effect change with coupling???
Co
s s
s s
Au
Quantum Nano Engineering Lab 10/23/2015 7 L a b Coupling NPs to superconductors through organic molecules
E. Katzir, et al. Appl. Phys. Lett . 98 223306 ( 2011). E. Katzir, et al. Phys. Rev. Lett. 108, 107004 (2012). E. Katzir, et al. Euro-physics letters 108 37006 (2014).
superconductors plays the role of the “known” system
1) Transport through molecules can be studied using the superconductors. 2) We can change the superconducting surface using the hybrid layers.
Quantum Nano Engineering Lab 10/23/2015 8 L a b Introduction to superconductivity
Characteristics of superconductors. Superconductor material has ZERO electrical resistance. H.K Onnes 1911
1957 BCS theory : Bardeen, Cooper, Schrieffer- Superconductivity as a microscopic effect caused by a "condensation" of pairs of electrons. Cooper pairs
1986 Johannes Georg Bednorz and Karl Alexander Müller - High Tc
Non BCS
Quantum Nano Engineering Lab 10/23/2015 9 L a b This talk is related to the 4th superconductors Nobel price The Nobel Prize in Physics 2003 Alexei A. Abrikosov, Vitaly L. Ginzburg, Anthony J. Leggett
Abrikosov- The sensing technique
1.0 1.02
1.00
0.8 Ginzburg – Motivation 0.98
0.6 0.96 6.5 7.0 7.5 8.0
RESISTANCE (arbitrary units) T [K] 0.4 I=1mA H=0.4 T 0.2 Leggett Explanation? MPS DiSilane 0.0 Hex Disilane
RESISTANCE units)(arbitrary 6.0 6.5 7.0 7.5 T [K]
Quantum Nano Engineering Lab 10/23/2015 10 L a b Type II superconductivity – Mixed state
Hc2
Abrikosov Vortex solid Hc1
Meissner State B = 0
- M
H Quantum Nano Engineering Lab 10/23/2015 11 L a b Current transport through Abrikosov Vortex lattice
Lorentz Force• F = J × B Causes vortex motion• Electric field E = v X B
Can not carry any bulk current
Quantum Nano Engineering Lab 10/23/2015 12 L a b Pinning
; Schematic illustrations of 3 different vortex pinning scenarios. (a) Negligible pinning; vortices form a lattice. (b) Strong pinning, large anisotropy. (c) Strong pinning, small anisotropy. FROM Jenny Hoffman (Harvard) .
Quantum Nano Engineering Lab 10/23/2015 13 L a b Peak effect (NbSe2) Small Angle Neutron Scattering (SANS) gives structure of the vortex lattice H Below peak – Long Neutron beam range order exists
Correlation volume
Vc is large
12 T = 5 K E = 1mV/cm 10 Above peak – 8 No long range order
6 Vc is small
(mA)
c
I 4
2 Peak effect Low T materials 0 c 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 H H (T) X. S. Ling et al, PRL T Quantum Nano Engineering Lab 10/23/2015 14 L a b Proximity Effect in superconductors Andreev reflection
Quantum Nano Engineering Lab 10/23/2015 15 L a b Our System
Disilane molecules
Nb film Sapphire Substrate
MPS DiSilane Hex DiSilane Top view
Quantum Nano Engineering Lab 10/23/2015 16 L a b Peak effect as a coupling sensor
1.0 1.02
1.00
0.8 0.98
0.6 0.96 6.5 7.0 7.5 8.0
RESISTANCE (arbitrary units) T [K] 0.4 I=1mA H=0.4 T 0.2 MPS DiSilane 0.0 Hex Disilane
RESISTANCE units)(arbitrary 6.0 6.5 7.0 7.5
T [K] 1.0 1.02 H=1.1 T H=1.0 T H=0.4 T 1.01
We are pleased to inform you that your article, 0.8 1.00 "Using the peak effect to pick the good 0.99 0.98 0.6 5.0 5.5 6.0 6.5 7.0 7.5
organic couplers," published in Appl. Phys. RESISTANCE (arbitrary units) T [K] Lett. 98, 223306 (2011) 0.4 has been selected for the June 2011 issue of I=1mA APL: Organic Electronics and Photonics 0.2 MPS H=0.4 T DiSilane H=1.0 T 0.0 Hex DiSilane H=1.1 T
RESISTANCE units)(arbitrary 3 4 5 6 7 T [K]
Quantum Nano Engineering Lab 10/23/2015 17 L a b STM Results
1
D = 0 . 81 meV 0 4 0 4 MPS
1.0 1.02 AFM of Au dot H=1.1 T H=1.0 T H=0.4 T 1.01
0.8 1.00 0.99
0.98 0.6 5.0 5.5 6.0 6.5 7.0 7.5
RESISTANCE (arbitrary units) T [K] 0.4 Proximity effect!!! Oded Millo STM I=1mA 0.2 MPS H=0.4 T DiSilane H=1.0 T 0.0 Hex DiSilane H=1.1 T
RESISTANCE units)(arbitrary 3 4 5 6 7 T [K] Quantum Nano Engineering Lab 10/23/2015 18 L a b We do have proximity effect!!! We have proximity effect through a molecule when the coupling is strong (small policemen is helping)!!! What will happened in the weak coupling regime? What will happened if we changed to high Tc materials? What will happened if we take magnetic nano particles? Can we have proximity effect with chiral molecules, Where no standard Andreev reflection can occur?
Quantum Nano Engineering Lab 10/23/2015 19 L a b Surprise-Weak coupling limit improving superconductors 50nm Nb film 150nm Nb film
clean sample
6 disilane and 10nm
] 4
[
T
/d MPS
R and 5nm
d 2 disilane H=0 Oe and 5nm I=2 mA 0
0.85 0.90 0.95 1.00 1.05 1.10 Normalized crtical temperature
MPS OTS
Quantum Nano Engineering Lab 10/23/2015 20 L a b Control linkers experiments
1.0 4 Before Attachment Vthreshold=0.5 mV 0.15 H=0 Oe After OTS Attachment 3
H=0 Oe 0.8 2
Ic [mA] I=2 mA I = 2mA 1 H=0 Oe 0.10 0.6 7.4 7.6 7.8 8.0 8.2 8.4 T [K]
]
0.4
R 0.05 R[ After Attachment Clean 1st Clean 2nd 0.2 Clean 3rd Before Attachment 0.00 0.0 7.5 8.0 8.5 9.0 7.2 7.6 8.0 8.4 T[K] T [K] Non linking OTS molecules Density of gold NPs changes
Quantum Nano Engineering Lab 10/23/2015 21 L a b Above and below Tc
15K
2711 on Dot IV SM2:4K27DTIV 600
400 4K
200
0
Current (pA) -200
-400
-600 -30 -20 -10 0 10 20 30 Sample Bias [mV]
Quantum Nano Engineering Lab 10/23/2015 22 L a b Matching Fields
1.0 After Attachment Before Attachment 0.8 H=9000 Oe Tc=6.6K Tc=6.65K 0.6 I=2mA
]
0.4
R[ 0.2
0.0 6.2 6.4 6.6 6.8 7.0 T [K]
1.0 After Attachment Before Attachment 0.8 H=0 Oe I=2mA Tc=7.65K Tc=7.9K 0.6
]
0.4
R[ Vortex-Rectification Effects in Films with Periodic Asymmetric 0.2 Pinning, J. Van de Vondel, C. C. de Souza Silva, B.Y. Zhu, M. Morelle, and V.V. Moshchalkov, 0.0 Phys. Rev. Lett., 94, 057003 (2005). 7.2 7.4 7.6 7.8 8.0 8.2 T [K]
Quantum Nano Engineering Lab 10/23/2015 23 L a b STM measurements showing the main spectroscopic features observed at 4.2K
Clear proximity (below TC) 3 1 1
2.5 D=0.80 meV
D=0.81 meV 2 0 0 -4 0 4 -4 0 4 . units)
(arb 1.5 /dV dI 1
0.5 -4 -2 0 2 4 Sample Bias (mV)
Quantum Nano Engineering Lab 10/23/2015 24 L a b STM Results Summary a) b) 8 5 Tc[Bare]=7.1K H=0 Oe Clean Sample Tc[Bare]=7.8K H=0 T I=2 mA I=2mA 6 4 DiSilane diSilane
] ] and 10nM 3 MPS and and 10 nm
/K Bare Nb MPS 10 nm
4
[
[
and 5nM 2 DiSilane
dR/dT
2 dR/dT and 5nM 1 OTS and 10nm 0 0 0.95 1.00 1.05 1.10 0.95 1.00 1.05 1.10 1.15 1.20 Normalized Critical Temparature Normalized critical Temperature 3 1 2.5 2 1.5 1
0 (arb.dI/dV units) -4 0 4 0.5 -4 -2 0 2 4 Sample Bias (mV) Quantum Nano Engineering Lab 10/23/2015 25 L a b (b) Co Cobalt Nano Particles S S
Si Si O O O O O O Nb2O5 Nb
high purity Low purity
0.07 REF REF 0.8 DS+Co NP 0.06 DS+Co NP
0.05 0.6 Tc=7.545 K Tc=7.565 K Tc=9.14K Tc=9.2K 0.04
0.4
0.03
0.02 R[Ohm]
Resist [Ohm] 0.2 0.01
0.00 0.0 -0.01 9.05 9.10 9.15 9.20 9.25 9.30 7.50 7.52 7.54 7.56 7.58 7.60 Temperature [T] T[K]
Quantum Nano Engineering Lab 10/23/2015 26 L a b STM Cobalt
Quantum Nano Engineering Lab 10/23/2015 27 L a b Density of Vo NPs
Quantum Nano Engineering Lab 10/23/2015 28 L a b High Tc material Optimally doped LSCO
La2-xSrxCuO4
Quantum Nano Engineering Lab 10/23/2015 29 L a b Superconductors surface coupling measurements summary
3 1 1 Critical current 2.5 D=0.80 meV
D=0.81 meV Actual behavior 2 0 0
. . units) -4 0 4 -4 0 4 arb
Weak (
1.5
dV / coupling dI
1 Expected curve
0.5 -4 -2 0 2 4 Sample Bias (mV) Critical Temperatures DT Actual behavior Weak coupling
Expected curve
Quantum Nano Engineering Lab 10/23/2015 30 L a b Strange Proximity Effects
Long range collective proximity effect Approaching zero-temperature metallic states in mesoscopic superconductor–normal– superconductor arrays
Serena Eley, Sarang Gopalakrishnan, Paul M. Goldbart and Nadya Mason
NATURE PHYSICS VOL 8 j 59 JANUARY 2012
Conducting Vs non conducting proximity Measurement of junction conductance and proximity effect at superconductor/semiconductor junctions Michael Vissers, Victor K. Chua, Stephanie A. Law, Smitha Vishveshwara, and James N. Eckstein
Quantum Nano Engineering Lab 10/23/2015 31 L a b Ginsburg Nobel Lecture Nobel Lecture: On superconductivity and superfluidity ~what I have and have not managed to do! as well as on the “physical minimum” at the beginning of the XXI century* REVIEWS OF MODERN PHYSICS, VOLUME 76, JULY 2004
“However, having familiarized myself with the paper of Little (1964), I put forward straight away Ginzburg, (1964) a quasi-two-dimensional model, wherein a plane conductor is in contact with a dielectric, say, a dielectric film. We termed the development of this version—the alternation of thin conducting layers with dielectric layers—a sandwich…”
Did we combine Ginsburg dream with molecular electronics recent knowledge?
Quantum Nano Engineering Lab 10/23/2015 32 L a b Mechanism?
•Enhancement of superconductivity by Anderson localization induced by pair pinning (Burmistrov, I.S., Gornyi, I.V. & Mirlin, A.D.
reduce the TC of the bare thin Nb films. •Noffsinger, J. & Cohen, M.L. Phys. Rev. B 81, 214519 (2010). • Coulomb interaction between electrons in neighboring planes increase cooper paring. (“Some Thoughts About Two Dimensionality and Cuprate Superconductivity”, Anthony J. Leggett)
We like to speculate that we have found the first step of the route to fulfill Ginsburg dream
Quantum Nano Engineering Lab 10/23/2015 33 L a b Suggested Model The critical temperature increases only if the following conditions occur:
i) Moderate matrix element mixing -The matrix element mixing the electron states in the NPs and the Nb film, , must be of moderate values - small enough to keep electrons basically localized, but large enough to provide significant tunneling probability.
ii) Large density of states - The density of states in the non-superconducting subsystem (in Au) should be large.
iii) Small electron-electron pairing -The electron-electron pairing potential in the superconducting subsystem ( in Nb) should be small.
iv) Linkers vibrational modes -There must be vibrational modes in the organic linker that can mediate the coupling between the electronic states in the Nb film and the gold NPs.
Little, W.A. “Possibility of Synthesizing an Organic Superconductor” Phys. Rev. 134 . A 1416 (1964).
Quantum Nano Engineering Lab 10/23/2015 34 L a b Model in detail
Two-band BCS Hamiltonian in the form
nmsu Hn,,,,,,,,,',,',, c n c n c n c m c s c u . ,
nmsu **r'''' r r r r r drdr The matrix element of electron- n,,,, m s u electron effective interaction potential
g g224 g T1.13 exp11 11 12 , g2 N N 2 , g N ce2g 2 12 11 22 1212 11 11 1111 12
For a large mixing term gg12 11 1 T can be higher than the bulk values Tce1.13 exp c g12
Quantum Nano Engineering Lab 10/23/2015 35 L a b We do have proximity through a molecule
Why? We don’t know!!!
• Two opposite channels of a hole and an electron passing through the molecules (both HOMO and
LUMO). Co
s s • Chiral molecules and triplets superconductivity? s s
SC
Quantum Nano Engineering Lab 10/23/2015 36 L a b Applications ??? Maybe for low dissipation logic devices Reduce the high level of energy dissipation associated with the present semiconductor-based integrated-circuit
Combine: Superconductivity and Spintronics
Quantum Nano Engineering Lab 10/23/2015 37 L a b Spin electronics - Spintronics • Consuming lower power than the conventional charge based semiconductor technologies • Circuitry can be scaled down. • Processing speeds can be faster. But: • Materials Problem • Large currents to generate spins
Quantum Nano Engineering Lab 10/23/2015 38 L a b Spintronics Devices
The 2007 Nobel Prize in Physics was awarded to : Albert Fert and Peter Grünberg for the discovery of GMR
Quantum Nano Engineering Lab 10/23/2015 39 L a b The CISS effect
The CISS effect- Chiral induced Spin Selectivity.
P P S S
Quantum Nano Engineering Lab 10/23/2015 40 L a b Spin dependent transport through . double stranded DNA Chiral Induced Spin Selectivity - CISS
8 26 bp 4 26 bp
0 -4 -8
8 40 bp 4 40 bp
0 -4
-8 8
dI/dV Current (nA) 50 bp 50 bp 4
0 -4 -8 8 40 bp 40 bp 4 On Au On Au
Zuoti Xie, Tal Markus, Sidney Cohen, Zeev Vager, 0 -4 Rafael Gutierrez, Ron Naaman -8 Nano Letters, 11, 4652–4655 (2011). -2 -1 0 1 2 -2 -1 0 1 2 Voltage (V) Voltage (V)
Quantum Nano Engineering Lab 10/23/2015 41 L a b The Charily Molecular based Universal Memory
Fast Dense Non- Power Volatile efficient
nm size transport Unit size 10nm stable No back scattering The industry needs are met without compromising in cost, compatibility to standard Si process & complexity of design
Quantum Nano Engineering Lab 10/23/2015 42 L a b Si based CISS devices
Potential difficulty- pin-holes in the organic monolayer. The problem was solved by evaporating thin layer (3-5 nm) of AlOx on top of the organic monolayer.
Nature Communications 4, 2256 DOI: 10.1038 (2013).
Highlighted in Nature "Nanotechnology: A memory device with a twist" 7.8.2013 http://www.natureasia.com/en/re search/highlight/8613
Quantum Nano Engineering Lab 10/23/2015 43 L a b Optically induced local magnetic memory
Highly localized magnetization device • (measured with MFM)
532nm Circular Polarized Beam
5nm Au 1.5nm Co Nano Letters 2014
44
Quantum Nano Engineering Lab 10/23/2015 44 L a b CISS May Address the Material Problems in Spintronics • Consuming lower power than the conventional charge based semiconductor technologies • Circuitry can be scaled down. • Processing speeds can be faster. However, in devices made of standard magnetic materials, large charge currents are required to generate sufficiently high spin currents, causing considerable Joule heating!!!
Quantum Nano Engineering Lab 10/23/2015 45 L a b Superconducting Spintronics
Superconducting Spintronics NATURE PHYSICS 11 307 (2015) Jacob Linder and Jason W. A. Robinson
Not Simple and required careful layers growth!!!
Quantum Nano Engineering Lab 10/23/2015 46 L a b Chiral proximity effect
Tunneling spectra measured on Nb film 1.2 on which chiral polyalanine a-helix 1.0 molecules were adsorbed (Tc = 7 K).
Three main types of spectroscopic 0.8 features were observed. Smeared superconducting gaps (red curve in (a)), dI/dV (arb. u.) 0.6
smeared gaps with a small ZBCP 0.4 embedded inside -15 -10 -5 0 5 10 15 Sample Bias (mV)
1.10
1.05
1.00
s s
dI/dV (arb. u.) 0.95
Nb 0.90
-15 -10 -5 0 5 10 15 Sample Bias (mV) Quantum Nano Engineering Lab 10/23/2015 47 L a b Simple superconductivity spintronics main idea
STM tip
Ferromagnet
contact Tunnel barrier Chiral layer
contact S
Quantum Nano Engineering Lab 10/23/2015 48 L a b Many thanks to
Our Group: Dr. Shira Yochelis, Eyal Cohen, Eran Katzir, Avner Neubauer, Guy Koplovitz, Oren Ben Dor, Ido Eisnberg, Ohad Westrich, Matan Galanty. Nir Peer, Chen Alpern; Amir Ziv, Aviya Perlman Illouz, Kuti Uliel
And
Grzegorz Jung Physics department , Ben Gurion University Beer Sheva Israel
Ron Naaman Department of Chemical Physics, Weizmann Institute, Rehovot 76100, Israel
Nadav Katz, Yaov Kalcheim, Oded Millo , Racah Institute of Physics, Hebrew University, Jerusalem 91904, Israel
Uri Banin Department of physical chemistry , Hebrew University, Jerusalem 91904, Israel
Financing:, ISF, ISF-BICORA, DARPA, MOD, Israel Taiwan, Magneton Capital Nature , FTA , Peter Brojde center, MOS, Volkswagen, Leverhulme Quantum Nano Engineering Lab 10/23/2015 49 L a b