CONTROL your SPIN

Au2Mn

Maria Pascale

University of Maryland

NIST Center for Neutron Research

N

S

N

S

N

S

N

S

N

S

N

S

N

S N

S
Body Centered Tetragonal

Background on Au2Mn 

Au

Mn
Background on Au2Mn 

• Ferromagnetic within each x y plane

• Helicoidal (Helical) Structure 

Pressure Temperature 

Wilson M. N., Karhu E. A., Lake D. P., Quigley A. S., Meynel S., Bogdanov A. N., Fritzche H., Rößler U. K., Monchesky T. L. “Discrete Helicoidal States in Chiral Magentic Thin Films”, Physical Review B 88(21) (2013): 

Au

Mn

Spin

Body Centered Tetragonal
Background on Au2Mn 

• Ferromagnetic within each x y plane

• Helicoidal (Helical) Structure 

Pressure Temperature 

Wilson M. N., Karhu E. A., Lake D. P., Quigley A. S., Meynel S., Bogdanov A. N., Fritzche H., Rößler U. K., Monchesky T. L. “Discrete Helicoidal States in Chiral Magentic Thin Films”, Physical Review B 88(21) (2013): 

Wayne R. C., Smith F. A. Journal of Physics and Chemistry of Solids, 30(184) 1969
Motivation

• Spin Properties 

have only been 

tested down to 

77 K and up to 

8.83 kbar

• Single crystal 

has not been 

made
Au2Mn Crystal 

Fabrication

Tetra Arc

Czochralski

Process

http://www.miracrys.com/CCinit.php?id=technologyam_4

Seed / 

Pulling 

rod

Ingot
Atomic % Mn

Au2Mn Single Crystal Fabrication
Au2Mn Crystal Growth
MEASUREMENTS

X Ray Diffraction

Energy Dispersive Spectroscopy

Magnetic Susceptibility

Electrical Resistivity

Neutron Scattering
X-Ray Diffraction

Operates using Bragg’s Law 

Gives interatomic 

distances, which can 

be used to confirm or 

to deduce crystal 

structures 

Nave, R. HyperPhysics: Quantum Physics. “Bragg’s Law”. http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/bragg.html

nλ=2dsinθ
Meas. data:I-Lin-Au2Mn-3

Intensity (cps)

 0

 5000

 10000

 15000

Au3.248 Mn0.7 

Au3.248 Mn0.752, (2 0 0)

Au3.248 Mn0.752, (2 2 0)

Au3.248 Mn0.752, (3 1 1)

Au3.248 Mn0.752, (2 2 2)

2-theta (deg)

20 40 60 80

Pulled Sample: 

Primarily Au3Mn

X-Ray Diffraction

CAUTION!

XRD Data may 

be unreliable due 

to sample 

preparation
2 4 6 8 10 12 14

keV

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5 cps/eV

 Mn Au Mn Au 

Pulled Au-Mn Crystal Proportions vary slightly depending on the location in the material

Energy Dispersive Spectroscopy

El AN Series unn. C norm. C Atom. C Error

[wt.-%] [wt.-%] [at.-%] [%]

--------------------------------------------

Au 79 M-series 94.04 87.09 65.29 3.7

Mn 25 K-series 13.95 12.91 34.71 0.6

--------------------------------------------

Total: 107.99 100.00 100.00 Possibly mix of different structural phases
Magnetic Susceptibility

0.50

0.70

0.90

1.10

1.30

1.50

1.70

1.90

2.10

2.30

2.50

0.00 50.00 100.00 150.00 200.00 250.00 300.00

4πΧ (emu/Oe/mol)

Temperature (K)

4πΧ - T for 100.5 mg Au-Mn Alloy

ZFC Ferro

ZFC Para

FC Para

FC Ferro

TC= 130 K

S = 2 or 5

2

Magnetic response of a sample to an applied field ΧP = 

CC

TT−Θ
Why?

• Concerned about 

existence of different 

phases 

• Encourage steady state 

diffusion

• Obtain Au2Mn

• Increase Grain Size 

Au2Mn Crystal Fabrication

Anneal at 730 ̊C

Atomic % Mn
X-Ray Diffraction

Nave, R. HyperPhysics: Quantum Physics. “Bragg’s Law”. http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/bragg.html

Annealed Sample: 

Primarily Au3Mn

Remember... 

Potentially 

unreliable!
2 4 6 8 10 12 14

keV

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

 cps/eV

 Mn Au Mn Au 

Annealed Au-Mn Crystal Proportions vary slightly depending on the location in the material

Energy Dispersive Spectroscopy

Looks like Au2Mn!

Spectrum: AuMn_1 283

El AN Series unn. C norm. C Atom. C Error

[wt.-%] [wt.-%] [at.-%] [%]

--------------------------------------------

Au 79 M-series 88.65 86.35 63.84 3.9

Mn 25 K-series 14.01 13.65 36.16 1.1

--------------------------------------------

Total: 102.66 100.00 100.00
Annealed Sample: 

TC= above 320 K

Magnetic 

Susceptibility

Irreversibility 

implies magnetic 

ordering 
• The intrinsic property of a material to prevent the flow of 

electricity

• Calculated using the ρ =

RRRR

ll

=

VV

II∗ll

4 Point Test

I+

IV+ VCeRhSi3

V

A

SAMPLE

ll

I1

I2

Electrical Resistivity
Physical Property 

Measurement System

Electrical Resistivity
Neutron Scattering Disc Chopper Spectrometer

1.56 g

NIST NCNR Web Page for DCS https://www.ncnr.nist.gov/instruments/dcs/

• Cold Neutron 

Instrument 

• Time of Flight 

Spectrometer

• Closed Cycle 

Refrigerator: base 

temperature 2.6 K 
Neutron Diffraction Disc Chopper Spectrometer

Powder 

Diffraction 

Rings
Neutron Spectroscopy

Disc Chopper Spectrometer

Smith F. A., Bradley C. C., Bacon G. E. Journal of the Physics and Chemistry of Solids 27(928) 1965 

Magnetic Peaks

Structural Peak
Neutron Diffraction Disc Chopper Spectrometer

Magnetic Peaks

Structural Peak

Smith F. A., Bradley C. C., Bacon G. E. Journal of the Physics and Chemistry of Solids 27(928) 1965 
Au5Mn2: Continuity and Contrast

Smith J.H., Wells P. “Antiferromagnetism in Au5Mn2” Journal of the Physics and Chemistry of Solids 2:2(375) 1969

Au5Mn2 Au2Mn

T Order 354 365

At % Au 71 66

C Atom. C Error

[at.-%] [%]

--------------------

Au 63.84 3.9

Mn 36.16 1.1

EDS
Conclusions and Outlook 

• Structural phase homogeneity is a 

prevalent challenge 

• Fabricate a new sample

•Upcoming Experiment – Pressure and 

temperature dependence of spin 

angle using BT4 triple axis

Atomic % Mn
THANK YOU!

Mentor: Nicholas Butch 

Acknowledgements: I-Lin Liu, Kefeng Wang
• The tendency of the magnetic moments (spins) within a 

material to become aligned with an applied magnetic field

• Higher susceptibility = easier to redirect the spins

100.5 mg

27.1 mg

Prior to 

applied 

Field

Field 

Applied

Callister D. William, Rethwisch G. David. Fundamentals of Materials Science and Engineering: An Integrated Approach. “Magnetic Properties”. John Wiley & Sons, Inc. 2012. pg W25. http://phys.thu.edu.tw/~hlhsiao/mse-web_ch20.pdf

Susceptibility
• X-Rays interact with electrons to reveal

• Atomic structure and Lattice Parameters

• Phases and Orientations

• Thermal Expansion

• Advantages

• Can use small samples

• Little effect on sample

• Disadvantage

• Difficult to distinguish atoms of similar atomic number

• Hydrogen is virtually invisible

X-Ray Diffraction
Susceptibility

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

0.00 50.00 100.00 150.00 200.00 250.00 300.00

4πΧ (emu/Oe/mol)

Temperature (K)

4πΧ - T for 27.1 mg Au-Mn Alloy

ZFC Ferro

FC Para

ZFC Para

FC Ferro
Susceptibility

Transition (K) Grown: Top - 100.5 mg Grown: Middle - 27.1 mg Annealed

ZFC Tc 1 -70.56 AFM 110.87 FM

ZFC Tc 2 34.81 FM 229.92 FM 

FC Tc 1 -115.31 AFM 81.30 FM

FC Tc 2 195.58 FM 227.11 FM 
Annealed Sample

Energy Dispersive Spectroscopy
Susceptibility

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

0.00 50.00 100.00 150.00 200.00 250.00 300.00

Long Moment (4

π*emu/Oe/mol)

Temperature (K)

4πΧ - T for Au2Mn

Susceptibility

Annealed Sample: 

TC= above 320 K
Energy Dispersive Spectroscopy

e 1. -

e2.

How does EDS work?

eeeeeeeeeeeX-Ray

3. Output energies and their 

quantities are recorded 

4. Reports elements which are present 

and their proportional quantities 

Note:

The difference between electron levels is 

atom specific
• Properties and Proportions vary depending on the location in the material

Pulled Au-Mn Crystal

2 4 6 8 10 12 14

keV

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5 cps/eV

 Mn Au Mn Au 

El AN Series unn. C norm. C Atom. C Error

[wt.-%] [wt.-%] [at.-%] [%]

--------------------------------------------

Au 79 M-series 80.44 84.94 61.14 3.2

Mn 25 K-series 14.26 15.06 38.86 0.6

--------------------------------------------

Total: 94.70 100.00 100.00

Surface – Likely mix of Au3Mn and AuMn

Energy Dispersive Spectroscopy
Reference

Gold-Manganese Binary Diagram (1990 Massalski T.B.)

Publication year: 1990

Diagram type: binary phase diagram

Concentration range: full composition; 0-100 at.% Mn

Temperature: -100 - 1400 °C

Nature of investigation: experimental

Authors: Massalski T.B., Okamoto H.

Title: Au-Mn (Gold-Manganese)

APDIC diagram: No

Wilson M. N., Karhu E. A., Lake D. P., Quigley A. S., Meynel S., Bogdanov A. N., Fritzche H., Rößler U. K., 

MoncheskyT. L. “Discrete Helicoidal States in Chiral MagenticThin Films”, Physical Review B 88(21) (2013): 

Hand - http://www.animationmagazine.net/people/britishanimation-icon-john-coates-dies-at-85/

Yellow Submarine 

https://garinglenn.wordpress.com/2013/10/18/magic-wandand-quick-select-tools/

My Materials Textbook! 

http://phys.thu.edu.tw/~hlhsiao/mse-web_ch20.pdf

Callister D. William, Rethwisch G. David. 

Fundamentals of Materials Science and Engineering: 

An Integrated Approach. “Magnetic Properties”. John 

Wiley & Sons, Inc. 2012. pg W25. 

http://phys.thu.edu.tw/~hlhsiao/mse-web_ch20.pdf
2 4 6 8 10 12 14

keV

0

1

2

3

4

5

6

 cps/eV

 Mn Au Mn Au 

Electron Diffraction Spectroscopy

Inner Core – Primarily Au2Mn

El AN Series unn. C norm. C Atom. C Error

[wt.-%] [wt.-%] [at.-%] [%]

--------------------------------------------

Au 79 M-series 77.71 85.15 61.52 3.0

Mn 25 K-series 13.55 14.85 38.48 0.5

--------------------------------------------

Total: 91.26 100.00 100.00

2 4 6 8 10 12 14

keV

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5 cps/eV

 Mn Au Mn Au 

El AN Series unn. C norm. C Atom. C Error

[wt.-%] [wt.-%] [at.-%] [%]

--------------------------------------------

Au 79 M-series 94.04 87.09 65.29 3.7

Mn 25 K-series 13.95 12.91 34.71 0.6

--------------------------------------------

Total: 107.99 100.00 100.00

Outer Core – Likely Au3Mn 

and AuMn