1. César de Julián Fernández
Magnetoplasmonics II
César de Julián Fernández
Magnetic Materials Group
IMEM-CNR Parma

2. MAGNETO-PLASMONICS Magnetic Magnetoplasmonics (I) - IntroductionAu
Surface plasmon
resonance
Magnetic
Mulvaney MRS Bull (2001)
Light – Plasmon- Magnetism Magneto-optics
Hybrid Materials
Multifunctional Materials

3. Magnetoplasmonics (I) - Schedule
0. Introduction
1. Plasmonics a General phenomenology and materials b Applications of plasmonics 2. Magnetoplasmonics
a Plasmonics and magnetism?
b. Principles of Magneto-optics c Magnetoplasmonics materials and phenomena d Applications

4. A (brief) Introduction to Magneto-optics
Magnetoplasmonics (II) – Magneto-optics
A (brief) Introduction to Magneto-optics
The first MOKE measurement
J. Kerr Philos. Mag 5 (1878) 161

5. Magnetoplasmonics (II) – Magneto-optics
Change of the polarization of the light after going through a magnetized material

6. Faraday Effect MO effect for optical transmission Magnetic rotation
Magnetoplasmonics (II) – Magneto-optics
Faraday Effect
MO effect for optical transmission
Magnetic rotation
（Faraday rotation）F（Faraday Ellipticity）F
Absorption
Magnetic Circular Dichroism MCD
Comparison to Natural Optical Rotation
Faraday Effect is Nonreciprocal (Double rotation for round trip)
Natural rotation is Reciprocal (Zero for round trip)
Verdet Constant
F=VlH (For paramagnetic and diamagnetic materials）

7. Magnetoplasmonics (II) – Magneto-optics
Linearly polarized light can be decomposed to LCP and RCP
Difference in phase causes rotation of
the direction of Linear polarization (Faraday Rotation)
Difference in amplitudes makes
Elliptically polarized light (Faraday Elliticity)
In general, elliptically polarized light
With the principal axis rotated

8. Kerr Effect Reflexion Configuration Ellipsometry
Magnetoplasmonics (II) – Magneto-optics
Kerr Effect
Reflexion Configuration
Ellipsometry

9. Kerr Effect (MOKE) Magnetoplasmonics (II) – Magneto-optics
Surface sensibility
Small Effect
10-4
Sub-nanometric
sensibility
In metals  Penetration length tens of nanometers
Surface Magneto-optical Kerr effect: SMOKE

10. Magneto-optical tensor
Magnetoplasmonics (II) – Magneto-optics
Magneto-optical tensor
H=0 HZ
Magneto-optical components
Optical components
The change of sign comes from the Nonreciprocal nature of the MO effects

11. Kerr effect depends on relative orientation of M(B)
Magnetoplasmonics (II) – Magneto-optics M E εk θk x y z
Kerr effect depends on relative orientation of M(B) M E θk εk θ0 θ0 M E
Polar
 + ie = f(Mz)
Longitudinal
 + ie = f(Mx)
Transverse
Rpp = f(My)
(H) Mx
(H)
(H)
Optical properties are controlled by an external magnetic field or with the magnetic state

12. Magneto-optical tensor
Magnetoplasmonics (II) – Magneto-optics
Magneto-optical tensor
In Faraday Configuration (k ||M)
Faraday Configuration
MOKE Configuration
Magnetometry
Spectroscopy
Electronic properties
Magnetic properties MO

13. Origin of the MO effects
Magnetoplasmonics (II) – Magneto-optics
Origin of the MO effects
Faraday Effect
Drude model
Optical and MO properties
For Au (600 nm, B=1 T) exy=1.2·10-4 +i1.5·10-3
In metals, semiconductors, some paramagnetic materials and organic compounds

14. Without magnetization
Magnetoplasmonics (II) – Magneto-optics
Origin of the MO effects
Fermi Golden Rules
L=1
L=0
LZ=+1,0,-1
LZ=0
Jz=-3/2
Jz=-1/2
Jz=+1/2
Jz=+3/2
Exchange splitting
Exchange
+spin-orbit
Without magnetization
DL= ±1
Selectivity to some transitions
Quantum-mechanical approach

15. 1.Diamagnetic lineshape (A term)
Magnetoplasmonics (II) – Magneto-optics
MO transitions
Excited state
Ground state 0 1 2 
Without
magnetization
With
Lz=0
Lz=+1
Lz=-1
1+2
Photon energy
’xy
”xy
1.Diamagnetic lineshape (A term)
Like Faraday MO contribution

16. 2.Paramagnetic transitions (C term)
Magnetoplasmonics (II) – Magneto-optics
MO transitions
2.Paramagnetic transitions (C term)

17. For example: Magnetite
Magnetoplasmonics (II) – Magneto-optics
For example: Magnetite
centrosymmetric, octahedral site are parity forbidden.
ISCT: Intersublattice Charge transitions A B
IVCT: Intervalance charge transitions A  A ,B  B
Others: Crystal field transitions
Fontjijn et al. JAP 85 (1999) 5100

18. Calculations of the optical dielectric tensor
Magnetoplasmonics (II) – Magneto-optics
Calculations of the optical dielectric tensor
considering the band structure

19. Magnetoplasmonics (II) – Magneto-optics
MO effects are correlated with the magnetic anistropy
Oppeneer PRB 45 (1992) 1092
Osgood III PRB

20. Hence: Allowed MO transitions DL= ±1 Spin-orbit coupling
Magnetoplasmonics (II) – Magneto-optics
Hence:
Allowed MO transitions DL= ±1
Spin-orbit coupling
Several transitions
Paramagnetic + diamagnetic
Interband + Intraband
Magnetic (M) and non-magnetic (H) Materials
A brief Introduction to Magneto-Optics

21. Optoelectronics needs a Magnetoplasmonic solutions for MO isolators!!!
Magnetoplasmonics (II) – Magneto-optics
Applications
Magneto-Optical isolator
non-reciprocal photonic component which :
Transmits light in forward direction
Reflects light in backward direction
Role : protect telecom laser from prejudicial optical feedback
Material : iron garnet (transparent at telecom wavelength)
Expensive
No integration in optoelectronic devices
Need of appropriate polarizers to obtain the isolation effect
Weak MO effect => large interaction length needed
Optoelectronics needs a Magnetoplasmonic solutions for MO isolators!!!
Bi et al Materials, 6,

22. P Mg Purpose of magnetoplasmonics
Magnetoplasmonics (II) – Magneto-optics
Purpose of magnetoplasmonics
Control of MO activity with plasmon excitation P Mg
Control of plasmon properties with an external magnetic field

23. The wall of magnetoplasmonics
Magnetoplasmonics (II) – Magneto-optics
The wall of magnetoplasmonics
Structural / chemical modifications
Direct electronic
correlations
Magnetic
properties
Plasmonics
NANO
Surface modifications
Indirect
correlations
All chemico-physics
properties are modified

24. Magnetoplasmonics (II) – Magneto-optics
0. Introduction
1. Plasmonics a General phenomenology and materials b Applications of plasmonics 2. Magnetoplasmonics
a Plasmonics and magnetism?
b. Principles of Magneto-optics c Magnetoplasmonics materials and phenomena e Applications
MO in Plasmonics materials?
Plasmonics in Magnetic Materials?
Novel properties?

25. MO effects in non-magnetic conductors
Magnetoplasmonics (I) – MO effects in plasmonics
MO effects in non-magnetic conductors
Faraday Effect
Drude model
Optical and MO properties
For Au (600 nm, B=1 T) exy=1.2·10-4 +i1.5·10-3

26. Generalized Maxwell Garnett Equation for LSPR
Magnetoplasmonics (II) – MO effects in Plasmonics
Generalized Maxwell Garnett Equation for LSPR
Hui Appl. Phys. Lett. 50, 950 (1987)
Marinchio et al. Phys. Rev. B 85 (2012)

27. Phenomenological description
Magnetoplasmonics (II) – MO effets in Plasmonics
Phenomenological description
The MO effect is usually a weak correction
e=eO + De
The effective polarizability can be splitted into two terms B
The MO polarizability comes from:
In plasmonic materials: Lorentz force
In magnetic materials: SO coupling
Maccaferri et al. Phys. Rev. Lett. 111 (2013)
Marinchio et al. Phys. Rev. B 85 (2012)

28. MO in dots Magnetoplasmonics (II) – MO effets in Plasmonics
Sepulveda et al. Phys. Rev. Lett. 104 (2010)

29. LSPR with circular polarized ligth (Magnetic dichroism)
Magnetoplasmonics (II) – Magnetoplasmonics in Plasmonics
LSPR with circular polarized ligth (Magnetic dichroism)
Circular polarized plasmons
13 nm
Pineider Nano Letters 13 (2013) 4785

30. LSPR with circular polarized ligth (Magnetic dichroism)
Magnetoplasmonics (II) – Magnetoplasmonics in Plasmonics
LSPR with circular polarized ligth (Magnetic dichroism)
Circular polarized plasmons
DA (+H) = LCD-RCD
Generalized Maxwell-Garnett for circular plasmons
Weick, Phys. Rev. B 83, (2011)
Modulation of SPR by the magnetic field

31. Plasmonics in magnetic materials
Magnetoplasmonics (II) – Magneto-optics in Plasmonics
Also in SPP
Au/air Dk/k×B = 10-6
Co/air Dk/k×M =10-4
Very small effect.
Better magnetic materials?
Plasmonics in magnetic materials
Too much losses!!
Wallis PRB 9 (1974) 3424
Armelles Adv. Optical Mater. 1 (2013) 10–35

32. LSPR in magnetic materials
Magnetoplasmonics (II) – Magnetoplasmonics in Plasmonics
LSPR in magnetic materials
Mie Calculation (n=1.5) P
(eV) e1
633 nm e2 Au
8.9
-11.7
1.26 Ag
9.2
-18.3
0.48 Co
9.74
-12.5
18.4 Fe
17.0
-1.03
17.6 Ni 9
-13.0
16.3
Nickel is the best!!!
But always dumping
Chen Small 7, (2011) 2341–2347

33. LSPR in magnetic NPs SPR in nUV
Magnetoplasmonics (II) – Plasmonics in Magnetic nanostructures
LSPR in magnetic NPs
Co NPs
Clavero et al. J. Appl. Phys. 100, (2006)
Kalska et al. J. Appl. Phys. 98 (2005) 44318
Fe NPs
SPR in nUV
Mie model does not work
Electronic structure of Nano
Oxidation
Menendez et al.
PRB 65, (2002)

34. Mie Model The dipolar approximation is a painting of the Nature
Magnetoplasmonics (I) - LSPR
Mie Model The dipolar approximation is a painting of the Nature
Physicist
Plasmonist
Magnetist
Be a spherical non-interacting single domain cow
Be a spherical cow with
No friction
Be a spherical non-interacting dipolar cow

35. Magnetoplasmonics (II) –Plasmonics in Magnetic nanostructures
LSPR in Ni nanorods
Shape improves LSPR
LSPR moves to IR
Phase change allows observation of SPR
Chen Small 7, (2011) 2341–2347

36. LSPR in Magnetic nanorods
Magnetoplasmonics (II) –Plasmonics in Magnetic nanostructures
LSPR in Magnetic nanorods

37. Magnetoplasmonics (II) –Plasmonics in Magnetic nanostructures
LSPR in Ni nanorods
Change of sign of the Phase above and below the SPR
Novel concept o f sensing : Work with MOKE=0
Tunnability with the magnetic field
Bonanni Nano Lett. 2011, 11, 5333–5338

38. Magnetoplasmonics (II) – Magnetoplasmonics in Plasmonics
LSPR in nanorods
Interactions
Photonic crystals
Direct and SO modes
Maccaferri Nano Lett. 2016, 16, 2533−2542
Kataja Nat Comm. 6 (2015) 7072
Maccaferri et al. PRL (2013) 111,
Lodewijks Nano Lett. 2014, 14, 7207−7214
Zubriskyia Nano lett 15 (2015) 3204

39. Hybrid Magnetoplasmonics materials
Magnetoplasmonics (II) – Hybrid Magnetoplasmonics materials
Hybrid Magnetoplasmonics materials
Tunable optical properties
Enhanced Magneto-optical signals
NANO
Enhanced
anisotropy
Magnetically active
Plasmons
Magnetic
properties
Plasmonics
Proximity effects
Multilayers
Hetero-nanostructures
Garnet based

40. Au NPs- Bi-YIG Magnetic films
Magnetoplasmonics (II) – Hybrid Magnetoplasmonics materials
Garnet based Nanostructures
Au-gratings on Bi-YIG films
High transparency (in the IR)
Difficult to be prepared
Hybrid
Au NPs- Bi-YIG Magnetic films
Amplification of the MO signal
Belotelov Nature Comm 4 (2013) 2128
SPR modes in gratings
are controllec by MO signal
Tomita PRL 96(2006)
Fujikawa, JAP 103 (2008) 07D301
Plasmon assisted MO transparency

41. Iron oxide tetrapods & prisms
Magnetoplasmonics (II) – Hybrid Magnetoplasmonics materials
Iron
Hetero-nanostructures
Gold-Iron oxide
Heterodimers
Gold-Iron oxide
Flowers
oxide
ferrite
shells
Silver-Iron oxide
Heterodimers
Iron oxide tetrapods & prisms
With a silver sphere
Gold-Iron Alloy

42. Hetero-nanostructures, is it a good idea?
Magnetoplasmonics (II) – Hybrid Magnetoplasmonics materials
Hetero-nanostructures, is it a good idea? Au
Magn. Mater
Most magnetic materials absorb in the VIS
Heterodimers
Red Shift and dumping of SPR!
Problems in the reproducibility of the Nanostructures
Shi, Nano Letters 6 (2006) 875 J Phys Chem 117 (2013) Velasco J. Phys. D Appl. Phys. 48 (2015) ; Luchini Phys. Chem. Chem. Physi.17 (2015) 6087

43. Magnetoplasmonics (II) – Hybrid Magnetoplasmonics materials
Fe oxide
NPs
385 nm
421 nm
455nm
532 nm
633 nm
850nm
Li Nano Letters 5 (2005) 1689
suPREMO
Au ferrite shell
Wang Nano Letters 11 (2011) 1237
Jain Nanoletters 9 (2009) 1644

44. Magnetoplasmonics (II) – Hybrid Magnetoplasmonics materials
Au- NPs
Hetero-dimers
Core-shell
Dumping of plasmonic resonance

45. Au and Fe oxide Hetero-nanostructures
Magnetoplasmonics (II) – Hybrid Magnetoplasmonics materials
Au and Fe oxide Hetero-nanostructures
10 nm
4 nm
20-24 nm
8-10 nm
1 nm
8 nm

46. Au and Fe oxide core@shell
Magnetoplasmonics (II) – Hybrid Magnetoplasmonics materials
Au and Fe oxide
1 nm
1.5 nm
9 nm
Pure plasmonics!!!

47. Au and Fe oxide core@shell
Magnetoplasmonics (II) – Hybrid Magnetoplasmonics materials
Au and Fe oxide
10 nm
4 nm
New transitions
Sharp feature
in the plasmon energy range
Superparamagnetic AND strong diamagnetic response!

48. Au and Fe oxide Hetero-nanostructures
Magnetoplasmonics (II) – Hybrid Magnetoplasmonics materials
Au and Fe oxide Hetero-nanostructures
g-Fe2O3
CoFe2O4
CT : Charge transfer [Fe2+]t2g[Fe3+]eg
ISCT: Intersublattice CF (Fe3+)t2[Fe3+]eg
CT : [Co2+]t2g[Fe2+]t2g
CF : Crystal Field 4A2 4T1(P)
MO transitions depend structure and chemical properties
BUT also on size and surface effects
Correspondence between MO transitions and SPR

49. Magnetoplasmonics (II) – Hybrid Magnetoplasmonics materials
Multilayers
Hybrid trilayers
NM/MT/NM
Very small!
Au/air Dk/k×B = 10-6
Co/air Dk/k×M =10-4

50. Multilayers Magnetic field control of Plasmonics
Magnetoplasmonics (II) – Hybrid Magnetoplasmonics materials
Multilayers
Observation of Magnetic field SPP (Telmnov Nat. Photonics 4 (2010) 107)
Magneto-plasmonic interferometer
Telmnov Nat. Photonics 6 (2012) 728
Magnetic field control of Plasmonics
Active Optoelectronics devices

51. Large MOKE signal due to the field induced modulation of ksp
Magnetoplasmonics (II) – Hybrid Magnetoplasmonics materials
Multilayers
Large MOKE signal due to the field induced modulation of ksp
Safarov Phys Rev. Lett. 73 (1994) 3584; Herman Phys Rev B 64 (2001) Gonzalez- Diaz Phys. Rev. B 76 (2007)

52. Magnetic layer thickness Magnetic layer position
Magnetoplasmonics (II) – Hybrid Magnetoplasmonics materials
Multilayers
Magnetic layer thickness
Increases MO contribution
Increase Dumping
Plasmonic materials
Better Ag than Au
But oxidation
Magnetic layer position
Better nearby surface
But oxidation
Quality of the films
Epitaxial growth
Decreases roughness and interdiffusion
Improve magnetic properties
Ferreiro-Vila Phys. Rev B. 83 (2011) ; Gonzalez Phys. Rev. B 76 (2007)

53. New MPs nanomaterials Trilayers NM/MT/NM
Magnetoplasmonics (II) – Hybrid Magnetoplasmonics materials
New MPs nanomaterials
Trilayers NM/MT/NM Au Co Au
Films + Nanorods
Honey ordered holes
Nanorods

54. Applications Magnetoplasmonics (II) – Applications
Multifunctional Nanomaterials
Biomedicine – Pharmacology- Catalysis
Nanomaterials with Enhanced MO Signals
Optoelectronics -Telecommunications
Magnetic field active plasmonics devices
Optoelectronics –Telecommunications
Plasmon assisted magnetic recording
Data Storage
Sensors
Separation
Van Parys et al. APL 88 (2006)
Constructive interferences
non-reciprocal waveguide
Destructive interferences +M
MO material -M
Mach-Zehnder interferometer

55. Applications- Chemical and biochemical sensors
Magnetoplasmonics (II) – Applications
Applications- Chemical and biochemical sensors
Magnetic field assisted ATR devices
have higher sensibility than conventional ones!
G. Armelles et al. Adv. Optical Mater., 1, 10–35, 2013
B. Sepulveda et al, Opt. Lett 31, 1085 (2006)

56. Applications- Sensors
Magnetoplasmonics (II) – Applications
Applications- Sensors
Air (n=1)
Water (n=1.3)
Gas sensors
Biochemical sensors
Au/Co/Au BK7 in air
Au/Co/Au SF10 in water

57. Applications- Sensors
Magnetoplasmonics (II) – Applications
Applications- Sensors
Air (n=1)
Water (n=1.3)
Gas sensors
Biochemical sensors
BSA Au
Surface
MUA
Anti
Test with BSA and anti-BSA x8
S=155 RIU
× 2 Sensibility of high quality Au layer
Manera Sensors and Actuators B 179 (2013) 175

58. Applications- Sensors
Magnetoplasmonics (II) – Applications
Applications- Sensors
Maccaferri Nat. Comm. 6 (2015) 6150
Change of the 1/De with refraction index

59. I miss to speak on: Gratings , Antidots and other geometries
Magnetoplasmonics (II) – The end
I miss to speak on:
Gratings , Antidots and other geometries
Magneto-plasmonics crystals
Magneto-plasmonics in garnets, alloys and other materials
Magneto-plasmonics in microwaves : Magnonics
Dynamic of the plasmonic and magnetic materials
Plasmonic and inverse Faraday effect
Spin plasmonics
Plasmon assisted demagnetization processes

60. P Mg Magnetoplasmonics is in the kickoff
Magnetoplasmonics (II) – The end
Magnetoplasmonics P Mg
Control of MO activity with plasmon excitation
Control of plasmon properties with an external magnetic field
is in the kickoff

61. The people Magnetoplasmonics Supported by N-Chem Univ. Pavia P. Ghigna
IMEM
F. Vita
F. Casoli
S. Fabbrici
F. Albertini
P. P. Lupo (ex)
INSTM – LAMM
G. Campo
E. Fantechi
C. Innocenti
A.Caneschi
F. Pineider (Pisa)
V. Bonanni (Milano)
R. Novak (ex)
L. Bogani (ex)
CNR
C. Sangregorio (ICCOM)
L. Cavigli (ICCOM)
R. Rella (IMM)
M. G. Manera (IMM)
Univ. Lecce
D. Cozzoli
Univ. Milano
A. Lascialfari
M. Scavini
P. Masala
CSIC- Spain
ID-12 ESRF
M. Garcia
J. Palomares
E. Paz
A. Garcia- Martin
A. Rogalev
V. Wilhelm
Supported by
N-Chem
Fondazione Cariplo
FUTURO
IN RICERCA

62. Thanks for your attention

63. Thiol capped Au- NPs Magnetic Materials Group IMEM-CNR
Magnetoplasmonics - Backstage
Thiol capped Au- NPs
Y. Yamamoto et al., Physical Review Letters 93, (2004).
XMCD  10-4, MS/ML  0.14
P. Crespo et al., Physical Review Letters 93, (2004).
Very recent: Huge Paramagnetism: Bartolomé Phys. Rev. Lett. 109, (2012)
Magnetic Materials Group
IMEM-CNR

64. Strong charge localization at the
Magnetoplasmonics (I) - Backstage
Thiol capped Au- NPs
Au NP
Strong charge localization at the
NP surface
NO SPR