Mapping of Magnetic Domains by MFM in Ni2MnGa

2008 ◽  
Vol 52 ◽  
pp. 115-119 ◽  
Author(s):  
Deepti Jain ◽  
Soma Banik ◽  
L.S. Sharath Chandra ◽  
S.R. Barman ◽  
R. Nath ◽  
...  
Keyword(s):  
Domain Walls ◽  
Alloy System ◽  
Optical Microscope ◽  
Magnetic Domains ◽  
Local Magnetization ◽  
Force Microscopy ◽  
Domain Structures ◽  
Two Samples ◽  
Ferromagnetic Shape Memory ◽  
Curie Temperature Tc

Influence of structural transition in the evolution of the magnetic domains in the ferromagnetic shape memory alloy system Ni2+xMn1-xGa is reported here using Magnetic Force Microscopy (MFM) studies. Studies reported are with two samples with their martensite transition temperature TM less than and greater than the Curie temperature Tc. Present results show an evolution of MFM across the Tc with a clear twin domains and sub domain structures inside the twins. The higher spatial resolution of MFM (~50nm) as compared to optical microscope (400nm) is useful in probing the domain walls. Force derivative of the MFM signal that may be used as an order parameter seems to scale the onset of magnetic order in the system. One can clearly see the vanishing of the MFM patterns for T>Tc. Results are discussed in the light of models available for tip-sample interactions that track the local magnetization.

scholarly journals Domain Structures across the Martensitic Transformation in Ni2+xMn1-xGa

2009 ◽  
Vol 635 ◽  
pp. 69-74
Author(s):  
Deepti Jain ◽  
Soma Banik ◽  
L.S. Sharath Chandra ◽  
S.R. Barman ◽  
R. Nath ◽  
...  
Keyword(s):  
Magnetic Force ◽  
Morphological Changes ◽  
Alloy System ◽  
Optical Microscope ◽  
Martensitic Transition ◽  
Ferromagnetic Shape Memory Alloy ◽  
Force Microscopy ◽  
Domain Structures ◽  
The One ◽  
Ferromagnetic Shape Memory

Evolution of domain structures across the martensitic transition (Tm) in the ferromagnetic shape memory alloy system Ni-Mn-Ga is studied using an optical microscope with a temperature variation. Compositions chosen have Tm < Tc, Tm = Tc and Tm > Tc, (Tc=Curie temperature) so that one can compare the nature of martensitic domains. There are no appreciable domain structures when Tm < Tc as compared to the one with Tm > Tc. However, giant morphological changes in the form of appearance of well-developed domains that are propagating with different directions are seen for the composition in which Tm=Tc. The results are discussed in the light of Magnetic Force Microscopy observations as well as giant entropy changes known to occur on samples with co-occurrence of Tm and Tc.

scholarly journals Visualization of magnetostructural transition in Heusler alloys by Magnetic Force Microscopy

2018 ◽  
Vol 185 ◽  
pp. 05004
Author(s):  
Pavel Geydt ◽  
Igor D. Rodionov ◽  
Alexander B. Granovsky ◽  
Ekaterina Soboleva ◽  
Egor Fadeev ◽  
...  
Keyword(s):  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Domain Walls ◽  
Heusler Alloys ◽  
Scanning Probe ◽  
Magnetic Domains ◽  
Magnetic Signal ◽  
Force Microscopy ◽  
Magnetostructural Transition ◽  
Probe Microscope

Magnetostructural transition was observed in Ni-Mn-In-Cr Heusler alloy with help of Magnetic Force Microscopy (MFM). The crystal structure of a sample and characteristic temperatures of the phase transition were controlled by roentgenostructural phase analysis and magnetometry, respectively. It appeared prominently important to prepare the surface of the sample until the nanometer level of surface roughness. Magnetic study performed with scanning probe microscope revealed existence of magnetic domains, which were spread across the surface evenly. Further studies revealed that intensity of magnetic signal decreases as fading out of the contrast of the MFM images. It was found that location of domains shifted after the heating/cooling cycle above Curie temperature for the studied alloy. Location of new domain walls appeared correlating with surface scrapings and defects, whilst it became independent from those after heating until just 70°C. The mechanism behind the observed transition is proposed.

Effects of a Large Content of Yttrium Doping on Microstructure and Magnetostriction of Fe83Ga17 Alloy

2019 ◽  
Vol 288 ◽  
pp. 27-36
Author(s):  
Li Juan Zhao ◽  
Xiao Tian ◽  
Zhan Quan Yao ◽  
Xuan Zhao ◽  
Ojiyed Tegus
Keyword(s):  
Magnetic Domain ◽  
Melting Furnace ◽  
Optical Microscope ◽  
Vacuum Arc ◽  
Force Microscopy ◽  
Domain Structures ◽  
Arc Melting ◽  
Bcc Structure ◽  
Magnetostriction Coefficient ◽  
Surface Morphologies

As-cast (Fe0.83Ga0.17)100-xYx (x=0, 3, 6 and 9) alloys were prepared by non-consumable vacuum arc melting furnace under a protective argon atmosphere. The crystal structures and surface morphologies of the alloys were studied by X-ray diffraction (XRD), optical microscope (OM) and scanning electron microscopy (SEM), combined with energy dispersive spectroscopy (EDS), respectively. The surface domain structures were observed by atomic force microscopy (AFM). The magnetostriction coefficients of the alloys were measured by strain gauging method. The results showed that the as-cast Fe83Ga17 alloy was composed only of a single phase of A2 with bcc structure, whereas the ternary Fe-Ga-Y alloys contain multiphase structure, besides the A2 phase, (FeGa)17Y1.76 new phases are observed as well, and an elemental yttrium phase appeared when the yttrium content increased to x=6 and x=9. Doping with yttrium have an effect on the change of magnetic domain structure of the binary alloy. With increasing x, the magnetostriction coefficient of the (Fe0.83Ga0.17)100-xYx alloys decreased sharply. The minimum magnetostriction coefficient is reduced to 12 ppm at the magnetic field of 426kA/m when x=9.

scholarly journals Investigations of ferroelectric polycrystalline bulks and thick films using piezoresponse force microscopy

2019 ◽  
Vol 475 (2223) ◽  
pp. 20180782 ◽  
Author(s):  
Hana Uršič ◽  
Uroš Prah
Keyword(s):  
Domain Walls ◽  
Thick Films ◽  
Piezoresponse Force Microscopy ◽  
Force Microscopy ◽  
Domain Structures ◽  
Atomic Force ◽  
Ferroelectric Domain Structure ◽  
Converse Piezoelectric Effect ◽  
Non Destructive

In recent years, ferroelectric/piezoelectric polycrystalline bulks and thick films have been extensively studied for different applications, such as sensors, actuators, transducers and caloric devices. In the majority of these applications, the electric field is applied to the working element in order to induce an electromechanical response, which is a complex phenomenon with several origins. Among them is the field-induced movement of domain walls, which is nowadays extensively studied using piezoresponse force microscopy (PFM), a technique derived from atomic force microscopy. PFM is based on the detection of the local converse piezoelectric effect in the sample; it is one of the most frequently applied methods for the characterization of the ferroelectric domain structure due to the simplicity of the sample preparation, its non-destructive nature and its relatively high imaging resolution. In this review, we focus on the PFM analysis of ferroelectric bulk ceramics and thick films. The core of the paper is divided into four sections: (i) introduction; (ii) the preparation of the samples prior to the PFM investigation; (iii) this is followed by reviews of the domain structures in polycrystalline bulks; and (iv) thick films.

Scanning electron microscopy with polarization analysis: An update

1991 ◽  
Vol 49 ◽  
pp. 764-765
Author(s):  
J. Unguris ◽  
M. W. Hart ◽  
R. J. Celotta ◽  
D. T. Pierce
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Domain Walls ◽  
Domain Wall Motion ◽  
Optical Recording ◽  
Polarization Analysis ◽  
Magnetic Domains ◽  
Magnetic Microstructure ◽  
Domain Structures ◽  
Scanning Electron

Over the past ten years the technique of scanning electron microscopy with polarization analysis (SEMPA) has rapidly evolved from a scientific curiosity to a useful analytical tool for looking at a material's magnetic microstructure. Several reviews of the technique have been published elsewhere. SEMPA has been successfully used to analyze various technological problems such as: noise in magnetic and magneto-optical recording media, domain wall motion in thin film recording heads, and domain structures in small Permalloy shapes. Basic science applications of SEMPA include quantitative studies of the influence of the surface on the structure of magnetic domains and domain walls, and studies of magnetic microstructures in ultra-thin (0.1 - 1 nm) ferromagnetic films. Many current applications of SEMPA make use of the technique's surface sensitivity to probe the magnetism of thin films and multilayers.

Inspection and Manipulation of Ferroelectrics on the Nanometer Scale

1999 ◽  
Vol 574 ◽  
Author(s):  
L. M. Eng
Keyword(s):  
Domain Walls ◽  
Near Field ◽  
High Vacuum ◽  
Polarization Vector ◽  
Optical Microscope ◽  
Ferroelectric Materials ◽  
Ultra High Vacuum ◽  
Atomic Scale ◽  
Dynamic Force ◽  
Force Microscopy

AbstractThe increasing interest in scanning probe instruments (SPM) stems from the outstanding possibilities in measuring electric, magnetic, optical, and structural properties of surfaces and surface layers down to the molecular and atomic scale. For the inspection of ferroelectric materials both the scanning force microscope (SFM) and the scanning near-field optical microscope (SNOM) are promising techniques revealing information on the polarization vector and the electric field induced stress within a crystal. Polarization sensitive modes are discussed as is friction force microscopy, dynamic force microscopy (DFM) and voltage modulated SFM. From these measurements, 180° domain walls (c-domains) are resolved down to 4 nm, while 3-dimensional polarization mapping in ferroelectric BaTiO3 ceramics reveals a 25 nm resolution. On the other hand, non-contact DFM measurements in ultra-high vacuum are able to resolve ferroelectric surfaces down to the atomic scale. Then also the chemical heterogeneity at the sample surface is differentiated from ferroelectric domains down to a 5 nm lateral resolution, taking advantage of the short range chemical forces. SNOM in contrast probes the optical properties of ferroelectric crystals both in transmission and reflection. Here image contrast arises from changes in the refractive index between different domains as well as at domain walls. In addition, SPM instruments are used for the local modification of ferroic samples by applying a relatively high voltage pulse to the SPM tip. Domains with diameters down to 30 nm are thus created with the size depending on both the switching and material parameters.

scholarly journals Imaging of Magnetic Domains and Domain Walls in Spherical Fe-Si Powder Using Magnetic Force Microscopy

2014 ◽  
Vol 126 (1) ◽  
pp. 92-93 ◽  
Author(s):  
M. Strečková ◽  
M. Baťková ◽  
I. Baťko ◽  
H. Hadraba ◽  
R. Bureš
Keyword(s):  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Domain Walls ◽  
Magnetic Domains ◽  
Force Microscopy

High Damping in Ferroelectric and Ferrimagnetic Ceramics

2006 ◽  
Vol 319 ◽  
pp. 157-166 ◽  
Author(s):  
Gilbert Fantozzi ◽  
E.M. Bourim ◽  
Sh. Kazemi
Keyword(s):  
Internal Friction ◽  
Curie Temperature ◽  
Domain Walls ◽  
Relaxation Mechanism ◽  
Ferroelectric Ceramics ◽  
Metallic Materials ◽  
Magnetic Domains ◽  
Damping Materials ◽  
High Level ◽  
Curie Temperature Tc

High damping materials exhibiting a loss factor higher than 10-2 are generally considered as polymer or metallic materials. But, it will be interesting to consider ferroelectric or ferrimagnetic ceramics, in which internal friction can be due to the motion of ferroelectric or magnetic domains. High level of internal friction can be obtained in these ceramics in a given temperature range. In the case of ferroelectric ceramics, hard ferroelectrics, such as BaTiO3 or PZT, can show some relaxation peaks below the Curie temperature due the motion of domain walls and the interaction between the domain walls and the oxygen vacancies or cationic vacancies. In the case of ferrimagnetic ceramics, some anelastic manifestations due to the ferrimagnetic domain walls appear below the Curie Temperature TC. These peaks are linked to the interaction of domain walls with cation vacancies or cation interstitials or the lattice. Above the Curie temperature, a relaxation mechanism due to the exchange of cations Mn3+ and their vacancies on octahedral sites should occur.

Meso- to nano-scopic domain structures in high Curie-temperature piezoelectric BiScO3–PbTiO3 single crystals of complex perovskite structure

2020 ◽  
Vol 8 (21) ◽  
pp. 7234-7243
Author(s):  
Zeng Luo ◽  
Zenghui Liu ◽  
David Walker ◽  
Steven Huband ◽  
Pam A. Thomas ◽  
...  
Keyword(s):  
Curie Temperature ◽  
Single Crystals ◽  
Domain Walls ◽  
Piezoresponse Force Microscopy ◽  
High Curie Temperature ◽  
Complex Perovskite ◽  
Force Microscopy ◽  
Local Distortion ◽  
Multi Scale ◽  
Domain Structures

Multi-scale domain structures in the BiScO3–PbTiO3 single crystal are imagined and analyzed by birefringence imaging microscopy (BIM) and piezoresponse force microscopy (PFM), revealing the local distortion in the vicinity of the domain walls.

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