Electronic Noise Due to Thermal Stripe Switching

Transcription

1 Electronic Noise Due to Thermal Stripe Switching E. W. Carlson B. Phillabaum Y. L. Loh D. X. Yao Research Corporation

2 Solid Liquid Gas

3 Crystals Fluids

4 Crystals Fluids Liquid Crystals Smectic Nematic Hexatic Cholesteric...

5 Crystals Fluids Liquid Crystals Smectic Nematic Hexatic Cholesteric... Glass and Amorphous solids

6 Crystals Fluids Liquid Crystals Smectic Nematic Hexatic Cholesteric... Glass and Amorphous solids Superfluid

7 Metals

8 Metals Band Insulators

9 Band Insulators Metals Semiconductors

10 Band Insulators Magnets Metals Semiconductors

11 Band Insulators Metals Semiconductors Ferro- Magnets Antiferromagnets Loh, Yao, EC PRB 2008 Yao, Loh, EC, Ma PRB 2008 Frustrated Magnets

12 Band Insulators Metals Semiconductors Loh, Yao, EC PRB 2008 Yao, Loh, EC, Ma PRB 2008 Frustrated Magnets Ferro- Magnets Antiferromagnets Superconductors EC et al., PRL 2003 Vortices

13 Band Insulators Metals Semiconductors Loh, Yao, EC PRB 2008 Yao, Loh, EC, Ma PRB 2008 Frustrated Magnets Ferro- Magnets Antiferromagnets Superconductors Vortices EC et al., PRL 2003 Quantum Hall Phases

14 Band Insulators Metals Semiconductors Loh, Yao, EC PRB 2008 Yao, Loh, EC, Ma PRB 2008 Frustrated Magnets Ferro- Magnets Antiferromagnets Superconductors Electronic Liquid Crystals Vortices EC et al., PRL 2003 Quantum Hall Phases

15 How we classify phases By the symmetry of long distance and long time properties Liquid Crystals Crystal Smectic Nematic Liquid Periodic (two directions) Periodic (one direction) Oriented Smooth (at long lengths and times)

16 Kohsaka et al., Science 315, 1380 (2007) STM, 4K Strong Correlations and Disorder Many degrees of freedom Spin Charge Orbital Lattice Dagotto, Science 309, 257 (2005) Proposed CMR state for Manganites Strong Correlation + Many DOF Many Phases Possible Different Phases Compete Competing Phases + Disorder Nanoscale pattern formation Complexity

17 A Way Forward Important nanoscale structure missed by the definiton of a phase! PROBLEM: Most theoretical and experimental tools are designed to characterize and detect long distance behavior Kohsaka et al., Science 315, 1380 (2007)

18 A Way Forward Important nanoscale structure missed by the definiton of a phase! PROBLEM: Most theoretical and experimental tools are designed to characterize and detect long distance behavior Kohsaka et al., Science 315, 1380 (2007) One Solution: Exploit Disorder, Using Noise and Nonequilibrium Effects to Characterize and Detect Nanoscale Pattern Formation

19 Cuprate Superconductors Brittle Ceramic Not Shiny Not Metallic Discovered in 1986 and still unexplained There is still no consensus on the phase diagram Is our outdated definition of a phase hindering progress?

20 Cuprate Superconductors Copper Oxygen Planes Other Layers Layered structure quasi-2d system

21 Cuprate Superconductors T Dope with holes Superconducts at certain dopings AF SC Oxygen Copper x

22 Cuprate Superconductors High pairing scale Short range order may be key Pseudogap: Many possible phases. Which one(s) is(are) happening? Disorder only compounds the problem! Stripes in cuprates? So far, detected in only a subset of materials Are they ubiquitous? Even short stripes can generate pairing Hard to detect! Disorder (chemical dopants) Rounds transitions Can destroy order! Temperature AF How do we define and detect phases with nanoscale pattern formation? Pseudogap +?? SC Doping

23 What's a Stripe? Most Ordered Less Ordered Unidirectional Spin and Charge Density Wave Unidirectional Charge Density Wave

24 What's a Stripe? Most Ordered Less Ordered Unidirectional Spin and Charge Density Wave Unidirectional Charge Density Wave

25 What's a Stripe? Most Ordered Less Ordered Unidirectional Spin and Charge Density Wave Unidirectional Charge Density Wave Even Less Ordered Oriented Charge (nematic)

26 Stripes in what probes? Hayden et al., Nature (2004) YBCO6.6 Neutron Scattering (bulk probe) LaSrCuO, LaCuO, YBaCuO (not BiSrCaCuO) Howald et al., PRB (2003) Scanning Tunneling Microscopy (surface probe) BiSrCaCuO BSCCO Zhou et al., Science (1999) Angle-Resolved Photoemission Spectroscopy (surface probe) BiSrCaCuO, YBaCuO LNSCO

27 Stripes + Disorder Random Field Ising Model Stripes lock to a crystal direction Cu-O plane Ising Nematic OR σ = 1 for horizontal stripe patch σ = -1 for vertical stripe patch Disorder favors one direction locally RANDOM FIELD ISING MODEL

28 Random Field Ising Model Two Dimensions Three Dimensions Temperature Ordered Disordered Temperature Ordered Disordered Random Field Strength Random Field Strength

29 Noise: Snap, Crackle, Pop Pencil Fire Popcorn Snap Crackle Pop Snap: Crackle: Pop: One large, system-size event Many events at random times, of random sizes. Many small, same-sized events at random times

30 Transport Stripe Patches Resistor Network Easy conduction Maps To Hard conduction Calculations: Monte Carlo Simulation of random field Ising Model Each configuration maps to a resistor network R xx and R yy calculated via bond propagation algorithm (Frank et al., PRB 1988) (Generalized to planar Ising models: Loh, EC, PRL 2006)

31 Transport Stripe Patches Resistor Network Easy conduction Maps To Hard conduction Resistance Anisotropy and RFIM Magnetization exhibit hysteresis Magnetization = orientational order M, (R xx -R yy )/(R xx +R yy ) H Orientational Order (R xx -R yy )/(R xx +R yy ) LXL = 300X300 T=0; Δ = 2.8 J; R large /R small = 2

32 Confined Geometries: Telegraph Noise Experiment YBCO nanowire (underdoped) Bonetti et al., PRL 93, (2004). T=100K 500nmX250nm Large switch 5 patches Theory R large /R small = 2 Size: 6X6 patches Disorder R=2.8 J T =.5 J Dimension = 2 EC et al., PRL 96, (2006) x Stripe correlation length ~ 40nm(from neutron data) see also Reichhardt et al, Europhys. Lett. 2005

33 That was for the normal state... Temperature Transport Anisotropy AF SC Doping

34 That was for the normal state... Temperature Transport Anisotropy AF Superfluid Anisotropy Doping SC

35 Calculations: Superfluid Density Anisotropy Monte Carlo Simulation of random field Ising Model Each configuration maps to Josephson Junction Array (JJA) Monte Carlo simulation for each JJA pattern Josephson Junction Array J w J s Maps to J s J w

36 Superfluid Density Anisotropy Josephson Junction Array J w J s Maps to J w J s

37 Superfluid Density Anisotropy Josephson Junction Array J w J s Maps to J w n 0.8 T c RFIM > T c SC J s n x n y R = 1 J s = 2 J w = 1 J = T

38 Superfluid Density Anisotropy Josephson Junction Array J w J s Maps to J w n 0.8 T c RFIM > T c SC n 8 T c RFIM < T c SC J s n x n y R = 1 J s = 2 J w = 1 J = n x n y R = 1 J s = 20 J w = 10 J = T T

39 Hysteretic Superfluid Density Anisotropy Apply an orienting field, H e.g., Uniaxial Strain on a Thin Film Ordered Δ=1 Js=2 Jw=1 L = 8 T=0,.5,1 Stripe Orientation Orienting Field Superfluid Anisotropy Orienting Field Intermediate disorder: Weak disorder within planes, Strong disorder between planes. Planes snap individually with B. Phillabaum, Y. Loh

40 Comparisons to STM Low Temperature Electronic Glass with Unidirectional Domains Experiment Theory Ca 1.88 Na.12 CuO 2 Cl 2 T=4.2K Kohsaka et al., Science 315, 1380 (2007) Layered system J =J /10 (Ising couplings) T=1.5J Δ=1.5 (disorder strength)

41 Prediction: Telegraph Noise in STM Stripe Glass Variance R=1.5 T=0.5 Active Regions are at Domain Boundaries Place STM tip on a line at a stripe boundary ON OFF Telegraph Noise

42 Time Average Variance Stripe Glass R=2.5 T=0.5 R=2.5 T=1.0 R=2.5 T=1.5

43 Detecting Correlations Other possible sources of telegraph noise: Bad tip Defects hopping on surface Power Spectrum Single uncorrelated switcher: Lorentzian power spectrum Interactions cause deviations Power spectrum is impractical for second noise

44 Spatial and Temporal Correlations in Noise R=2.5 T=0.5

45 In-Situ Test for Correlations "On-the-fly" Reblocking Algorithm (Kent et al., J. Comp. Chem. 2007) Block size m MC timestep Each block spin is the average of the ones below it. Accumulate averages and variances for each block size m. Memory requirement = O(log 2 N), rather than O(N)

46 In-Situ Test for Correlations Block Variance Low m deviations from horizontal line indicate correlations

47 Research Corporation Conclusions Stripes + Host crystal + Disorder = Random Field Ising Model Disorder makes stripes hard to detect. Need new ways to probe: Noise, Hysteresis Transport: Switching noise in small systems in R xx Orientational Order measured by R xx -R yy Similar for Superfluid Anisotropy Scanning Noise Spectroscopy (STM): Telegraph Noise at Domain Boundaries Active regions are at stripe cluster boundaries More active regions as temperature is raised Local Noise Maps out Stripe Clusters Spatial and Temporal Noise Correlations