This presentation include : 1. Multiferroic 2. Possible cross- couplings 3. History and Applications 4. Ferromagnetic nature 5. Ferroelectric nature 6. Piezoelectric and Subgroups 7. Perovskite structure and Perovskite based multiferroics 8. My future work on particular type of multiferroic material .............

1. STUDY OF MULTIFERROIC PROPERTIES OF
DOPED AND PURE LaFe𝐎 𝟑
Supervisor – Dr.OroosaSubohi
Presenter – Ashutosh Tiwari (MS18PHY021)

2. Multiferroics
- Multiferroics is special class of solid state materials that simultaneously
exhibit more than one type of ordering, including ferromagnetic,
ferroelectric, and ferroelasticity order phases coexist.
- Magnetic order is conventionally driven by exchange interactions between
magnetic dipoles, originating from unfilled shells of electron orbitals.
Electric order is the result of ordering of local electric dipoles. Elastic order
is the result of ordering of atomic displacements due to strain
Multi Ferroic

3. Possible Cross-Coupling in Multiferroics
• The coupling between Ferro – phases and
Piezo elastic properties are to be done.
• Coupling facilitates the direct control of
ferromagnetic and ferroelectric properties via
externally applied stress and in addition of
that converse effects also true.
• Possible couplings are : 1) Piezo-electric 2)
Piezo-magnetic 3) Magneto-electric 4) Elasto-
Magneto-Electric.
• Magneto-electric coupling will be focussed in
this Literature survey.

4. Why Magneto - electric coupling is unique ?
Magneto-electric multiferroic materials have the unique property that when
subjected to an applied external magnetic field, the electric polarization
modified and conversely Magnetization modified on the application of
electric field.
Electrically induced magneto-electric effect is defined as the change in the
magnetization (M) of the sample due to the application of an electric field
(E): 𝛼 𝐸 =
𝜕𝑀
𝜕𝐸
Similarly, the magnetically induced magneto-electric effect is the change in
the electric polarization (P) of the sample due to the application of a
magnetic field (H): 𝛼 𝐻 =
𝜕𝑃
𝜕𝐻
𝛼 𝐸
𝛼 𝐻
There are two possible types of “magneto-electric” couplings : Direct and Indirect
Direct coupling materials called “Single phase” multiferroic and Indirect coupling
material called “Composite” multiferroics

5. Historical Perspective
Multiferroic materials and the possibility of magneto-electric coupling – the induction of magnetization by an electric field
and the induction of electric polarization by a magnetic field in solids was first predicted by Curie in 1894 based on crystal
symmetry consideration. while the term magneto-electric coupling was first coined by Debye in1926.
In 1959, Dzyaloshinskii was the first to report a magneto-electric effect in anti-ferromagnetic Cr2O3 dielectrics.
After the Initial surge interest in magneto electric multiferroics has lost momentum with scientific community because their
were very few magneto electric coupling multiferroics found which display very less magneto electric coupling and not even
at room temperature. But from year 2000 to till today published articles (i.e. 16000 in 2013) and patents filed (i.e 1750 per
year from 2009 -2014) per year change drastically. Few multiferroics found which display large magnetoelectric coupling
value and show multiferroicity at room temperature.
Importance and Applications
- Multiferroic materials with semiconductors and spintronics materials, could, in future, replace the existing RAM’s and
computational technology based on semiconductors
- Electric polarization remain finite even after removing the electric field. This property used in non-volatile memory
devices, where the information remain stored in the electric polarization, even after removing the power of the device.
1) The most promising application of multiferroics is a multiferroic memory device where information can be written
electrically taking the advantage of lower power operation and read magnetically thus non-destructively.
2) Perovskite Oxides have found useful applications in solid oxide fuel cells, non-volatile magnetic memory devices, and
ultrasensitive magnetic readheads of modern hard disk drives.

6. Ferromagnetic :
• The magnetic flux generated by an electromagnetic
coil is the amount of magnetic field or lines of
force produced within a given area called “Flux
Density” (denoted by ‘B’). SI Unit is Tesla or Gauss.
• Magnetic field strength (i.e. H) depends on
number of turns, current and core material in coil.
SI Unit is A/m. Ratio of flux density to field
strength, 𝜇0 𝜇 𝑟 =
𝐵
𝐻
; 𝜇0 = 4 𝜋 × 10−7 N 𝐴−2 𝑜𝑟 H/m
“Partially filled orbitals are responsible for Magnetic
ordering in ferromagnets, so most of the
ferromagnetic materials are Conducters”
Some Ferromagnetic materials have a high retentivity
(magnetically hard), useful for producing permanent
magnets.
While other ferromagnetic materials have low
retentivity (magnetically soft), useful for producing
electromagnets, solenoids or relays.
Magnetisation or B-H Curve
Magnetic Hysteresis Loop
Magnetic Hysteresis Loops for Soft and
Hard Materials
1
2
3

7. Ferroelectric: Insulating materials
E
• Ferroelectric are majorly used in memory devices.
• Ferroelectric materials are spontaneously polarized i.e It is
polarized in the absence of external field.
• Each domain polarization has specific direction, but all domains
are oriented randomly so initially Overall polarization is zero.
• On application of Electric field domains aligned in one direction,
polarization saturates and crystal become single domain.
• 𝑃𝑠 - Spontaneous polarization ( By extrapolation of BC )
• Polarization remained even after removing electric field called
Retentivity or Remanent Polarization 𝑃𝑟 , information stored in
this Retained polarization.
• To make polarizatio again zero a Coercive field required in
opposite direction called coercive field 𝐸𝑐 .
• If Coercive field > Breakdown field , solid is not ferroelectric.
Ferroelectric have lack of center of symmetry
“Main focus to Increase the Remanent Polarization 𝑃𝑟 so that more
information can be stored non destructively “

8. Piezoelectric and Subgroups

9. Perovskites : A perovskite is any material with the same type of crystal structure as calcium titanium oxide
(CaTiO3), known as the perovskite structure. The general chemical formula for perovskite compounds is ABX3, where
'A' and 'B' are two cation of very different sizes, and X is an anion that bonds to both. The 'A' atoms are larger than
the 'B' atoms.
In the idealized cubic unit cell of such a compound, type 'A' atom sits
at cube corner positions (0, 0, 0), type 'B' atom sits at body-center
position (1/2, 1/2, 1/2) and ‘oxygen’ atoms sit at face centred
positions (1/2, 1/2, 0).
Complex perovskite structures contain two different B-site cations.
The B cations in simple perovskites are located in octahedral symmetry
in the BO6 octahedra.
The highly localized transition-metal 3d electrons fulfill the criteria for
magnetism.
The Basic Perovskite Structure
In most of the single phase multiferroic materials, the
Magnetoeletric coupling and their ordering temperature is too low.
The GaFeO3 is the good multiferroic. It is room temperature
piezoelectric as well as near room temperature ferrimagnetic
material.
Different type of perovskite based multiferroics :

10. • I will upload my whole work on doped and undoped LaFe𝐎 𝟑 once it is
completed …

11. Thank You
Ashutosh Tiwari
“StaySafeandHealthy”