Display the Experiment Proposals

Experiment: M1265

Magnetic phase diagram of the electron-doped high-temperature superconductor Nd2-xCexCuO4 and magnetic penetration depth of model hole-doped superconductor HgBa2CuO4+d

by the Greven/Luke/Uemura group

Active (Stage 2)
Spokespersons:
G.M. Luke (McMaster University)
M. Greven (University of Minnesota)
Y.J. Uemura (Columbia University)

Original Proposal for EEC meeting 200912M

Table of Contents

Detailed Information

Complete/Merged PDF M1265_200912M_merged.pdf
Form data only M1265_200912M.pdf
Detailed Statement proposal_triumf_ncco.pdf (376.64 kB)

Beam Shift Summary

12-hr ShiftsBeam Line / channelPriority
New Beam Requests
 12 M15

For measuring the magnetic penetration depth of HgBa2CuO4+d. Beam line M9 is also OK if available and if the luminosity is comparable to that of M15.

12 M15

For investigating the phase diagram of Nd2-xCexCuO4. Beam line M9 is also OK if available and if the luminosity is comparable to that of M15.

Committee Recommendations
 24 M

This proposal falls into two rather disparate parts. The first part of the proposal focuses upon a search for magnetic correlations in the archetypal electron-doped cuprate superconductor Nd2-xCexCuO4 for a range of concentrations, x. Although it has been previously suggested that long-range magnetic order associated with Cu ions coexists with superconductivity in these compounds, this is now known not to be the case. However the possibility of coexisting superconductivity and static short-range magnetic correlations remains an open question. The proposers argue that reported neutron measurements may have overestimated the extent of the magnetically ordered region of the phase diagram, and moreover that neutrons cannot provide a definitive answer to the question of short-range magnetism because of the relatively short time window of the neutron. The proposers suggest that µSR could resolve this issue. The Committee considered the problem and its solution to be sufficiently important to warrant the allocation of beam time.

In the second part of the proposal, it is proposed to measure the concentration and temperature-dependence of the penetration depth in HgBa2CuO4+d. This part seemed to be less compelling, but could nevertheless provide useful and interesting information, particularly in the overdoped regime.

Beam Shifts Used
 

11 shifts scheduled on Schedule 117.


Membership

G.M. Luke McMaster University Professor 20 % Spokesperson
M. Greven University of Minnesota Associate Professor 20 % Spokesperson
Y.J. Uemura Columbia University Professor 20 % Spokesperson
G. Yu University of Minnesota PDF 20 %  
T. Goko TRIUMF / Columbia University PDF 20 %  

Basic Information

Date Submitted
2009-11-09 22:45:16
Date Experiment Ready
2010-05-01
Summary *

We propose muon spin relaxation measurements on the archetypical electron-doped high-Tc cuprate Nd2-xCexCuO4 over a range of Ce concentration x.  These are high-quality samples that have been measured extensively with neutron scattering.  Measurements of the magnetic correlation length have revealed that in this system long-range magnetic order and superconductivity do not coexist (as previously thought).  The question remains open whether (short-range) static order does coexist with superconductivity.  The short time scales of neutron scattering (relative to muSR) are unable to solve this issue; preliminary muSR measurements on some of our samples have shown that neutron scattering indeed overestimates the extent of the magnetically ordered region of the phase diagram.  We wish to continue these measurements on a wider array of samples to conclusively determine the relationship between the antiferromagnetic and superconducting phases in this system.

In addition, we propose to measure the magnetic field penetration depth in the model superconductor HgBa2CuO4+d, and how this quantity evolves with temperature and hole doping.

Plain Text Summary *
We propose to investigate the magnetic phase diagram of the electron-doped high-temperature superconductor Nd2-xCexCuO4 using muSR. This study will extend our knowledge about the interplay between magnetism and superconductivity from neutron-scattering studies. We also propose to measure the magnetic penetration depth in the model hole-doped compound HgBa2CuO4+d.
Primary Beam Line
Base 1A
Secondary Channel
Base
M15
Primary / Secondary Beam
Energy (MeV)
500(MeV)
Intensity (uA)
100-150 uA(uA)
Particle Type
muon
Energy (MeV)
surface muons(MeV)
Spot Size (mm)
10 (diameter)(mm)
Production Target
Meson Target
1AT1: 1cmBe
Summary List of samples

Nd(2-x)Ce(x)CuO4   with x at about 10 values in the range of 0.117 to 0.15

HgBa2CuO4+d, one underdoped sample (Tc=74K), one optimally doped sample (Tc=95K) and one overdoped sample (Tc=80K)

μSR Spectrometers
LAMPF
TRIUMF Support (Resources Needed)
NSERC

This research is supported by NSERC-CIAM funding to Graeme Luke

Other Funding

This research is supported by NSF funding to Martin Greven

This research is supported by NSF-CIAM funding to Tomo Uemura

Muon Justification

MuSR is a demonstrated unique and strong probe for studying magnetism and superconductivity of correlated electron systems.

Safety Issues

We sometimes use specimens measured by neutron scattering, which could have a slight radioactivity due to neutron irradiation of the contained elements (Nd and Hg).  Proper official procedures will be followed for transportation and handling of such specimens.
The specimens are chemically stable in air and are not hazardous.

Proposals and Progress Reports

200912M (Original Proposal)