Supported by the National Science Foundation

DMR-1202033 (MWM), DMR-1405439 (DRT),

DMR-1157490 (NHMFL), and the

UF Center for Tomorrow’s Materials (Today!)

Mark W. Meisel and Group Members (past and present)

Department of Physics and NHMFL, University of Florida

Long-standing collaboration with Daniel R. Talham and his Group

Department of Chemistry, University of Florida

“Molecular Magnetism”: What is it? What it is NOT!

or “What I wish I knew when I was in your seat….”

Start with a Definition: (but avoid blathering….. on…. and…. on…. and….on….)

A short history of molecular magnetismhttp://www.unizar.es/magmanet/magmanet-eu/index.php?/short_history_of_molecular_magnetism.html

Molecular Magnetism Web: a gate to molelcular magnetiem(http://www.molmag.de) thanks to Jürgen Schnack

or is it Molecule-based Magnetism? (don’t trust Wikipedia….)

C. M. Hurd, Contemp. Phys. 23, 469-493 (1982)not comprehensive? where is:weak ferromagnetism,canted antiferromagnetism, …

Date: 1564

Title: Floridae

Cartographer:

Jacques Le Moyne de Morgues

http://scholar.library.miami.edu/floridamaps/first_spanish_period.php

An extra functionality dimension from ionic activity.The usual control parameters for

tuning the functionality of complex oxides—electric field E, which controls

polarization P; magnetic field H, which controls magnetization M; and stress σ,

which controls strain ɛ (A)—should be augmented (B) by the chemical potential µ to

capture the functionalities driven by mobile ions and defects in these materials (as

described by the concentration of mobile species, c).

S V Kalinin, and N A Spaldin Science 2013;341:858-859

Published by AAAS

The Art of Making a Good and Tasty Sandwich(culinary heterostructure)

salami

salami

A

B

A

A + B + A = A

A

B

C

B

A

A + B + C + B + A = B

ABA heterostructure ABCBA heterostructure

Chren pikantné

(Armoracia rusticana)

Thin breadPatina of strong mustardThick salamiPatina of strong mustardThin bread

A + B + C + B + A = D

D is new and dominate taste!

Recipe is same for nanostructures

where interfaces are important!

http://newyork.seriouseats.com/2010/10/

a-sandwich-a-day-fried-salami-at-eisenberg-sa.html

The Art of Making a Good and Tasty Sandwich(culinary heterostructure)

Alphabet Soup and Some Possible Recipes

Spin Crossover (SCO) S LS S HS + Electron Transfer =

Charge Transfer Induced Spin Transition (CTIST) S1 = 0 and S2 = 0 S1 = 1/2 and S2 = 3/2(“cooperative”, e.g. lattice distortion too)

Light-Induced Excited Spin State Trapping (LIESST)

Temperature

M = χ B

χ = C

T χ T

Talham – Meisel Chemistry-Physics Group Retreat Aug. 2014

PAQ and MKP: PhD theses

(2015)

Switching magnetism with light above 77 K in a bistable coordination polymer heterostructureOlivia N. Risset, Tatiana V. Brinzari, Marcus K. Peprah,Pedro A. Quintero, Mark W. Meisel, Daniel R. Talham, preprint

100 150 200 250 300

0.2

0.4

0.6

0.8

1.0

B = 100 G

Dark

Light

Ma

gn

etiz

atio

n [1

0-5 e

mu

G]

Temperature [K]

hν

CoFe@CrCrcore@shellnanoparticles

scale bar = 200 nm

Prussian Blue and Analogs: Magnetism

D. Davidson, L.A. Welo, J. Phys. Chem.

32 (1928) 1191.

J. Richardson, N. Elliott, J. Am. Chem. Soc.

62 (1940) 3182.

N. Holden, B. T. Matthias, P. W. Anderson,

H. W. Lewis, Phys. Rev. 102 (1956) 1463.

R.M. Bozorth, H.J. Williams, D.E. Walsh, Phys. Rev. 103 (1956) 572.

A. Ito, M. Suenaga, K. Ono, J. Chem. Phys. 48 (1968) 3597.

H.J. Buser, D. Schwarzenbach, W. Petter, A. Ludi, Inorg. Chem. 16 (1977)

2704. [x-ray structure of Fe4[Fe(CN)6]3 • xH2O]

P. Day, F. Herren, A. Ludi, H. U. Gudel, F. Hulliger, and D. Givord,

Hel. Chim. Acta 63 (1980) 148.

Reviews:

K. Dunbar and R.A. Heintz, Prog. Inorg. Chem. 45 (1997) 283.

M. Verdaguer and G.S. Girolami, “Magnetic Prussian Blue Analogs,” in

Magnetism: Molecules to Materials 5 (Wiley-VCH, 2004) 283.

man-made pigmentfrom early 1700’s

S = 1 eg

t2g

C-NFe3+

S=1/2 S=3/2

-20 0 20 4010

15

20

Magnetiza

tion (

arb

. units)

Time (Min)

Persistent Photoinduced Magnetism (PPIM)

T < TC

S = 0

t2g

eg

C-NFe2+ Co3+

S=0 S=0

Co2+

“Powders*”: O. Sato, T. Iyoda, A. Fujishima, K. Hashimoto, Science 272 (1996) 704

IrradiatedDark

“Perspective”: M. Verdaguer, Science 272 (1996) 698

* (K0.2Co1.4[Fe(CN)6] · 6.9 H2O)

10.3 Å

10.0 Å

Slide from J.-H. Park

H2OKCo Fe

C-N N-C

K0.2Co1.4[Fe(CN)6]·6.9H2O

0 10 20 30

0

1

2

3

4

5

0.0 0.5 1.0

2.5

3.0

3.5

4.0

4.5

5.0

(

10

-5 e

mu

/cm

2)

T (K)

(

10

-5 e

mu

/cm

2)

time (hours)

Persistent Photoinduced Magnetization

O. Sato et al., Science 272, 704 (1996).

Slide from D.M. Pajerowski

K0.2Co1.4[Fe(CN)6]·6.9H2O

H2OKCo Fe

C-N N-C0 10 20 30

0

1

2

3

4

5

0.0 0.5 1.0

2.5

3.0

3.5

4.0

4.5

5.0

(

10

-5 e

mu

/cm

2)

T (K)

(

10

-5 e

mu

/cm

2)

time (hours)

T = 5 K

Persistent Photoinduced Magnetization

O. Sato et al., Science 272, 704 (1996).

Slide from D.M. Pajerowski

Heterostructures of molecule-based magnets yield ….

0 20 40 60 800

5

10

15Light state

Magnetic r

esponse (

arb

. units)

Temperature (Kelvin)

Dark state

0 1 26.5

7.0

7.5

8.0

T = 60 K

Time (hours)

Light on

Pajerowski et al., J. Am. Chem. Soc. 132 (2010) 4058

… photocontrolled magnetism that is stable (> weeks) to high temperatures.

A

B

A100nm

A + B + A = D (“metamaterial”)

aka “Magnetolomics”

0 20 40 60 800.0

0.2

0.4

0.6

0.8

1.0

Single phase

Temperature (K)

MA

X

Heterostructure

FC in100 G

Persistent Photocontrolled Magnetism (PPCM) inNanoscaled Heterostructures of Prussian Blue Analogs(Prussian blue: man-made pigment from 1704)

A Ni-Cr

B Co-Fe

A 100nm

B A

Reproducible TastyProperties!

Films: Pajerowski et al.,J. Am. Chem. Soc.132 (2010) 4058

Core@Shell: Dumont et al.,Inorg. Chem.

50 (2011) 4295

B C

Core@Shell: C = Co-CrRisset et al., J. Am. Chem. Soc.

136 (2014) 15660

New Ingredient…same Tasty Properties!

Films with “spin crossover” (Fe-Pt SCO) materialGros et al., J. Am. Chem. Soc. 136 (2014) 9846

Mechanism? Irradiation with white light relaxes interface strain induced while cooling, causing rearrangement of magnetic moments near the interface.

Insight from Ni-Cr single component films studied by EPR at NHMFL.Pajerowski et al., Phys. Rev. B82 (2010) 214405

≈10 nm shell

Fe3+

Co2+

Rb+

H2O

CN-

H2O replaces CN ligand leaving a Fe

vacancy.

Rb sits in an

interstitial site.

FCC lattice

M. Verdaguer,

Science 272

(1996) 698

(and “charge balance”!)

Defects instructures are a level of Complexity!

Ingredient 1: Photoactive Component: CoFe Prussian Blue analogue (PBA)

Rbj Cok [Fe(CN)6]l • n H2O

(variables are j , k , l , n )

Note M-CN-M’bridging!

Co/Fe = 1.5

Co/Fe = 1.37

Co/Fe = 1.32

Co/Fe = 1.26

Co/Fe = 1.15

350 K50 K

5

0

High Spin

Low Spin

T vs. T

plots

Shimamoto, Ohkoshi,

Sato, Hashimoto,

Inorg. Chem.

41 (2002) 678

CTIST: Charge Transfer InducedSpin Transition (HS to LS by cooling)

HetroStructured Layered Film : Co-Fe / Ni-Cr (CN)6

~ Co-Fe

Co-FeNi-Cr

Ni-Cr

High TC

PhotoinducedMagnet ?

Co Fe Ni Cr

0

1 2 3

4

B

BA

A

A

B

A ~ 10 Å

A: Photoinduced Magnet

B: High TC Magnet

A + B = ?

Ideas motivated by: M. Nishino, Y. Yoshioka,

K. Yamaguchi, Chem. Phys. Lett. 297 (1998) 51

J.-H. Park, Ph.D. thesis (2006) Univ. of Florida

Ingredient 2: Ferromagnetic Component: NiCr Prussian Blue analogue (PBA)

Slide from J.-H. Park

Long-Range vs. Short-Range Ordering

Magnetic Coherence Length: ξ (T, spatial/spin dimensions, …)

Characteristic Length of Scale of Sample: ℓ(“structural coherence length”)

ℓ

ξ

ℓ < ξ : Short-Range “Order” (“spin liquid”):

Interactions/correlations at short distances

Fingerprints: Curie or Curie-like with

no TC , ...

ℓ > ξ : Long-Range “Order” (“spin solid”):

Interactions/correlations at long distances

Fingerprints: “bulk” TC , Coercive Magnetic

Field, …

Curie-Weiss Law: = _ C_

T+ Θ

ℓ

ξ

ℓ ~ ξ : “Intermediate Order” :

Fingerprints: 0 < Tc < Tc(bulk), ...ξ

ℓ

0 20 40 60 800

5

10

15Light state

Magnetic r

esponse (

arb

. units)

Temperature (Kelvin)

Dark state

0 1 26.5

7.0

7.5

8.0

T = 60 K

Time (hours)

Light on

D.M. Pajerowski et al., J. Am. Chem. Soc. 132 (2010) 4058

A

B

A100nm

0 20 40 60 800.0

0.2

0.4

0.6

0.8

1.0

Single phase

Temperature (K)

MA

X

Heterostructure

Result 1: Thin films ABA (NiCr-CoFe-NiCr) Prussian Blue analogues (PBA)

Extra Important Points:

White Light (vs monochromatic)

Lengths ≳ 50 nmsmaller lengths:N. Dia et al., Inorg. Chem. 52 (2013) 10264M. Presle et al., J. Phys. Chem. C 118 (2014) 13186

other morphologies: D.M. Pajerowski, PhD thesis (2010)

Low concentration(add very slow…)

NiIICl2K3CrIII(CN)6

Multilayered Heterotructure

CoIICl2K3FeIII(CN)6

RbCoFe PBA

KNiCr PBA

200nm

Control of the Nucleation

(10 x the excess ofCores vs. precursor)

Result 2: CoFe@NiCr-PBA core-shell nanoparticles

Slide from M.F. Dumont

0 20 40 60 80

0

10

20

30

40

(

cm

3 / m

ol C

oF

e)

T (K)

dark - light

0H = 100 G

0 20 40 60 800

50

100

150

200

250

(

cm

3 / m

ol C

oF

e)

T (K)

dark

light

0H = 100 G

0 20 40 60 800

40

80

120

(

cm

3 / m

ol C

oF

e)

T (K)

dark

light

0H = 100 G

0 20 40 60 800

20

40

60

(

cm

3 / m

ol C

oF

e)

T (K)

dark

light

0H = 100 G

0 20 40 60 80

0

10

20

30

40

(

cm

3 / m

ol C

oF

e)

T (K)

dark - light

0H = 100 G

0 20 40 60 80

0

10

20

30

40

(

cm

3 / m

ol C

oF

e)

T (K)

dark - light

0H = 100 G

~ 80 nm shell ~ 100 nm shell ~ 160 nm shell

Result 2: CoFe@NiCr-PBA core-shell nanoparticlesMechanism and Extent of Interface Strained Region

E.S. Knowles et al., Polyhedron 66 (2013) 153; E.S. Knowles, Ph.D. thesis (2013)

Result 3: CoFe@CoCr-PBA core-shell nanoparticles (Change of Ingredient)Mechanism and Extent of Interface Strained Region

Light-Induced Changes in Magnetism in a Coordination Polymer Heterostructure … Olivia N. Risset, Pedro A. Quintero, et al., J. Am. Chem. Soc. 136 (2014) 15660.

Interfaced Strained Region (ISR) extends to about 25 nm in Shell.

Thickness of Shell influences Core and ISR and Domain rearrangement.

Fe(azpy)[Pt(CN)4]

Agustí et. al. Chem. Mater. 2008, 20, 6721

a (Å) c (Å) Volume (Å3) Fe-Neq (Å) Fe-Nax (Å)

HS 7.41 ± 0.02 13.37 ± 0.05 734 ± 4 ------ ------LS 7.16 ± 0.04 12.98 ± 0.03 665 ± 6 ------ ------

Δ (HS→LS) 0.25 ± 0.04 0.39 ± 0.06 69 ± 7 0.18 ± 0.03 0.20 ± 0.03

a

c~ 300 K

S = 0 S = 2

Ingredient 1: Photoactive Component: Spin-crossover (SCO)Hofmann-like framework (Change of Ingredient)

Light-Induced Excited Spin State Trapping = LIESST

Result 4: Films of SCO Fe-Pt and NiCr-PBA (Change of Ingredient)

Light-Induced Magnetization Changes in a Coordination Polymer Heterostructure …Corey R. Gros, Marcus K. Peprah, et al., J. Am. Chem. Soc. 136 (2014) 9846.

SCO Fe-Pt

Glass

NiCr-PBA

Result 5: Platelets of SCO Fe-Ni and NiCr-PBA (Change of Ingredient)

NiCr-PBA/Fe(azpy)[Ni(CN)4] : Marcus K. Peprah, Corey R. Gros, et al., in preparation

100 150 200 250 300

0.2

0.4

0.6

0.8

1.0

B = 100 G

Dark

Light

Ma

gn

etiz

atio

n [1

0-5 e

mu

G]

Temperature [K]

hν

CoFe@CrCrcore@shellnanoparticles

scale bar = 200 nm

Result 6: CoFe@CrCr-PBA nanoparticles (Change of Ingredient)

Switching magnetism with light above 77 K in a bistable coordination polymer heterostructureOlivia N. Risset, Tatiana V. Brinzari, Marcus K. Peprah,Pedro A. Quintero, Mark W. Meisel, Daniel R. Talham, preprint

Early attempts and hints: Elisabeth S. Knowles, Ph.D. thesis (2013)

Now Persistent Magnetism changes thermally compromised by CoFe-PBA electron relaxation.

Can the Interface Strained Region magnetic domains possess memory to CrCr-PBA TC = 220 K?

Co/Fe = 1.5

Co/Fe = 1.37

Co/Fe = 1.32

Co/Fe = 1.26

Co/Fe = 1.15

Shimamoto, Ohkoshi,

Sato, Hashimoto,

Inorg. Chem.

41 (2002) 678

350 K50 K

350 K5 K

5

0

High Spin

Low Spin

T vs. T

plots

NaxCoy[Fe(CN)6]z •nH2O

T vs. T

plots

Persistent Photocontrolled Magnetism (PPCM) inNanoscaled Heterostructures of Coordination Polymers[PBA = Prussian blue analogue]

A NiCr-PBA

B CoFe-PBA

A 100nm

B A

Reproducible TastyProperties!

Films: Pajerowski et al.,J. Am. Chem. Soc.132 (2010) 4058

Core@Shell: Dumont et al.,Inorg. Chem.

50 (2011) 4295

B C

Core@Shell: C = CoCr-PBARisset et al., JACS136 (2014) 15660

New Ingredient…same Tasty Properties!

Films with “spin crossover” Fe-Pt SCO / NiCr-PBAGros et al., J. Am. Chem. Soc. 136 (2014) 9846

100 150 200 250 300

0.2

0.4

0.6

0.8

1.0

B = 100 G

Dark

Light

Ma

gn

etiz

atio

n [1

0-5 e

mu

G]

Temperature [K]

hν

CoFe@CrCrcore@shellnanoparticles

scale bar = 200 nm

Core@Shell:CoFe@CrCr-PBA

adding externalpressure…

add chemicaltuning…Road to 300 K?

1 2 3

4

5 Fe-Ni SCO / NiCr-PBA

6

7

Date: 1564

Title: Floridae

Cartographer:

Jacques Le Moyne de Morgues

http://scholar.library.miami.edu/floridamaps/first_spanish_period.php

Join the Exploration!

Learn the ABCD’s:Always Be Collecting Data

F3: Form Follows Function

SOC: Spin Orbit Coupling

Think and Do!

We are colleagues!

Now some “canned” slides for potential questions.

Rb0.8Ni [Cr(CN)6]0.7·nH2O

Phys. Rev. B 82 (2010) 214405

Demagnetizing Factors!

Magnetic anisotropy in thin films of Prussian blue analogues

Phys. Rev. B 82 (2010) 214405

D.M. Pajerowski, J.E. Gardner, M.J. Andrus, S. Datta,A. Gomez, S.W. Kycia, S. Hill, D.R. Talham, M.W. Meisel

116 GHz

External Pressure tuning of the Magnetic Response in CoFe-PBA

Domain distortion in CrCr-PBA persists to Tc,which is Pressure Depedent.

100 150 200 250 300

0.00

0.02

0.04

0.06

0.08

0.10

0.12 September 2014

MP163: 109BC1-2 : CoFe@CrCr

White Light (no filter)

FC in 100 G, 0H = 100 G

Optical Presssure Probe 2.0

[ M

da

rk (

T)

- M

ligh

t(T

) ]

/ M

da

rk(T

= 3

00 K

)

Temperature (K)

P = 2.55 GPa

irradiation at 80 K

CrCr-PBA

TC Bulk

CoFe-PBA

TCTIST

Result 7: CoFe@CrCr-PBA nanoparticles (Light and Pressure) (Change of Environment)

Z. Mitróová et al., Acta Phys.Pol. A 133 (2008) 469

E.S. Knowles,Ph.D. thesis (2013)

10.4 Å10.3 Å

10.0 Å

APS – ANL dataunder analysis…A. Felts et al.

Laure Catala and Talal Mallah and coworkers

Small (< 30 mn) core@shellCoFe-PBA@NiCr-PBA:

Linkage Isomerism? (unpublished)

M. Verdaguer and G.S. Girolami (2004):“The solid Prussian blue analogues can also suffer from one or more of the following problems: (4) Linkage Isomersism”

Time, strain, interface… Irreversible / Reversible

“High pressure neutron scattering of the magnetoelasticNi-Cr Prussian blue analogue,” D. M. Pajerowski, S. E. Conklin, J. B. Leão, D. Phelan, L. W. Harriger, Phys. Rev. B 91, 094104 (2015)

(and untold story of route to T > 200 K)

High-TC core-shells?

50 100 150 200 250 3000

1

2

3

4

M (

10

-5 e

mu G

)

T (K)

dark

light

0H = 100 GA

0 50 100 150 200 250 3000.0

0.5

1.0

1.5

M (

10

-3 e

mu

G)

T (K)

CAB

dark

light

0H = 100 G

*heterogeneous (“chunks” of B in sample)?E. S. Knowles et al., unpublished.

CoFe-PBA

NiCr-PBA

CrCr-PBA

Diamagnetic FeII(LS, S = 0) – CN - CoIII(LS, S = 0)

Ferrimagnetic FeIII(LS, S=1/2) – CN - CoII(HS, S=3/2)

O. Sato, Y. Einaga, A. Fujishima, K. Hashimoto, Inorg. Chem. 38 (1999) 4405.

T. Kawamoto, Y. Asai, S. Abe, Phys. Rev. Lett. 86 (2001) 348.

(ab initio quantum cluster calculations)

“Hunch”: distribution of energy barriers exist due to

local environment.

Photoinduced Magnetism in Cobalt-Iron Cyanide