# Presentation: 830405

## M. Hücker

**Manipulating Competing Order with High Pressure**

- Neutron Scattering Group
- (CMPMS)

**Correlated Electron Systems**
**(****Superconductivity, Magnetism, Electronic Order)**
** ****High Temperature Superconductors**
** ****Transition Metal Oxides **
** ****Ferroelectrics**
** ****Heavy Fermion Systems**
** ****Multiferroics**

**La****2-x****Ba****x****CuO****4**
**Charge & Spin Stripes**

**Notes:**
And one way to uncover these mechanism is to expose sample to extrem environment,
such as Temperature, H. E fields.

And there are only a small of them

Role of PG phase ranges from competing with SC to precursor of SC

Loss of magnetic order and concommitant quantum fluctuations of that 
previous order important for SC. Diagram 

## Single-Crystal XRD at Low Temperature

- LBCO

- CGO

- 1 mm

**Single-Crystal XRD at Low Temperature**

** ****Intensity ~10****-6**** off strongest Bragg Peak **
** ****Powder XRD not possible**
** ****E=100keV, 2•10****11**** photons/sec/mm****2**

- BW5-HASYLAB

## High Pressure Beamline at NSLS-II

** ****Single Crystal XRD **
** ****4-Circle Diffractometer**
** ****Point Detector (2D Detector optional)**
** ****Low Temperature**
** ****Flux >10****11****–10****12**** photons/sec on Sample**
** ****DAC (MAC,Toroid)**
** ****Sample Centering**

** ****M. v. Zimmermann, HASYLAB**
** ****J. M. Tranquada, G. Xu, Neutron Scattering Group**
** ****Y. J. Kim, University of Toronto**
** ****B. Wells, University of Connecticut**
** ****D. J. Buttrey, University of Delaware **
** ****C. C. Kao, Z. Zhong, NSLS**

## NSLS II 

**NSLS II **

**Paris Edinburgh Cell **

- 100 mm3
- 30 GPa
- 25 kg
- low T not so easy

**Diamond Anvil Cell **

- 0.0001 mm3
- 100 GPa
- small beam
- sample position
- pressure inhomogeneous

**ISIS**

**Notes:**
There is basically no limit as to what 

## Pressure and Superconductivity

**Yamada et al. JSSC 1989**

**Bozovic et al. PRL 2002**

**LSCO thin film**

**LSCO bulk**

**Gao et al. PRB 1994**

**Hg-1223 bulk**

**Pressure and Superconductivity**

**Pressure: **
**affects crystal structure and electronic band structure **

**buckled**

**flat**

**Notes:**
Flat planes are important for SC.
However, detailed forensic work has to be done to understand the underlying mechanisms which phase kills which and are actually good.

Tc propto 1/a*b
Intraplanar pairing interaction seem to be more important.
Pressure is a basic thermodynamic parameter, like temperature.
In most SC Tc decreases with increasing pressure.
In high Tc it is often the other way round.

## Competing order in LBCO

**single-crystal**
**HXRD**

**Notes:**
The stripe phase in LBCO is where charge and spin stripe order competes with supercondcutivity.
In this paricular case the stripe order occurs in a particular structure, the LTT phase. 
In the LTO or HTT phase Tc would describe the supercondcuting dome known for LSCO. 
Pressure can be used to suppress the LTT phase, and x-ray can evolution of the stripe order. 
As pressure is increased und SC comes up, we then can apply high magnetic fields to suppress
the supercondcutivity, and see what effect it has on the stripe order. This gives us unprecedented 
access to the interplay between stripe order and SC and the question whether stripes are competing or 
mediating SC.

## Charge Stripes under Pressure 

**Charge Stripes under Pressure **

**LTT **
**structure**

**Charge Stripes**

**Do stripes survive in flat planes when x=1/8?**

## Hole Crystallization in 2-Leg Ladder

**Hole Crystallization in 2-Leg Ladder**

**Blumberg et al. Science 2002**

**Rusydi et al.**

**Sr****14****Cu****24****O****41**

**Abbamonte et al.**

**RSXS**

- oxygen-K edge

**XRD: Zimmermann et al. PRB 2006**

**Notes:**
Doped ladder predicted superconductivity and formation of a hole-crystal due to many body interactions.
Proximity to charge ordered states general property of SC in cuprates.
Ca : Sr : Ba = 1.18 : 1.31 : 1.47

## 3 GPa

**3 GPa**

**4 GPa**

**7 GPa**

**NSLS/HASYLAB/NSLSII**

**100keV**

**Large Volume Pressure Cells for Single-Crystal X-ray Diffraction **

**100keV**

- Mini Toroid Cell

**1 cm **

**Notes:**
All other cells, like DAC and large Volume Paris-Edinburgh cells, will cost major efforts, to be operated at low temperatures.
One can certainly happy NSLS, and at the NSLS II.

## pressure cell: scattering/absorption

- pressure cell absorption:
- factor 10

## pressure sensor:  CuGeO3

- pressure sensor:  CuGeO3

- structural distortion at the spin Peierls transition at 14 K

## 100 keV beamline BW5 at HASYLAB, Hamburg

**100 keV beamline BW5 at HASYLAB, Hamburg**

- E-range:
- 60-200 keV
- Crystal type:
- Si/TaSi2 (100”)
- Si1-xGex (15”–70”)
- Our Exp: 35”
- E-resolution:
- 600eV at 100keV
- Flux(photons/s):
- 2e11/mm2 @ 100keV
- (100mA, 4.5GeV)
- Spot size:
- 0.5mm x 0.5mm to
- 6mm x 6mm
- Detector:
- N2 cooled Ge det.
- Wiggler:
- 2Tesla, 17 periods

## Competing Order

**Lattice density (pressure)**

**Charge density (doping)**

- CePd2Si2