Energy coupled to matter for magnetic alignment of rare earth–doped alumina

J. Phys.: Condens. Matter

Alpay

2019

Judicious doping of normally diamagnetic alumina (Al2O3) could lead to bulk magnetism that would enable the usage of cutting edge technology, such as magnetoforming, to create advanced systems that take advantage of the high chemical and physical resilience of alumina. This study builds upon initial results (Nykwest et al 2018 J. Phys.: Condens. Matter 30 395801) which have shown that alumina doped with magnetic elements such as Fe and Ni should exhibit heightened magnetic activity. Here we expand the analysis to several additional transition metals that are otherwise non-magnetic (Sc, Ti, V, Mn, and Co) and use density functional theory to understand the origin of the spin delocalization, as well as to predict the structural, electronic, energetic, and magnetic properties of doped -alumina. The results indicate that adding small concentrations of such elements to -alumina may increase magnetic activity by generating coordination environments with magnetic moments. Our findings show conclusively that significant spin delocalization can only occur when there are unpaired electrons in the transition metal eg states.

Section: Magnetic Moment and Spin Densitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Towards magnetic alumina: uncovering the roles of transition metal doping and electron hybridization in spin delocalization

J. Phys.: Condens. Matter

Alpay

2019

“…One possible approach to decreasing the scattering of light in polycrystal line alumina is through texturing, which can have a profound affect on the physical and optical properties of a material [6,7]. Research of slip cast doped alumina has shown that it is possible to texture alumina with the application of a strong external magn etic field [8][9][10]. Doping alumina in a way that leads to net unpaired electrons could strengthen the coupling between it and external magnetic fields, improving the effi ciency of texturing with a magnetic field and allowing for the creation of advanced high strength, chemically resistant sys tems such as spintronic and magnetic qubit systems [11].…”

Section: Introductionmentioning

confidence: 99%

Magnetic and energetic properties of transition metal doped alumina

J. Phys.: Condens. Matter

Rinderspacher

Elward

et al. 2018

A doped non-diamagnetic alumina (AlO) would enable the usage of cutting edge technology, such as magnetoforming, to create advanced systems that take advantage of the high chemical and physical resilience of alumina. This study elucidates the magnetic properties of Cr, Fe, Ni, and Cu doped α- and ϑ-alumina. Density functional theory was used to predict the structural, electronic, and magnetic properties of doped alumina, as well as its stability. The results indicate that the dopant species and coordination environment are the most important factors in determining the spin density distribution and net magnetic moment, which will strongly direct the ability of the doped alumina to couple with an external field. Similar coordination environments in different phases produce similar spin densities and magnetic moments, indicating that the results presented in this work may be generalizable to the other five or more phases of alumina not studied here.

“…It has been demonstrated that substituting a transition metal dopant could produce alumina that possesses both unpaired electrons and a net magnetic moment 12 . In addition, it was also determined that the delocalization of these unpaired electrons varied greatly between dopants 13 , which may affect the final magnetic properties of the doped system 14 . Previous work in metallic systems 15 – 17 has pointed toward enhanced magnetism near surfaces, where a transition in spin density from the bulk to the surface region was observed.…”

mentioning

confidence: 99%

Surface localized magnetism in transition metal doped alumina

Trujillo

Alpay

2021

Sci Rep

Alumina is a structural ceramic that finds many uses in a broad range of applications. It is widely employed in the aerospace and biomedical sectors due to its stability at high temperatures and in harsh chemical environments. Here, we show that magnetism can be induced at alumina surfaces by doping with 3d transition metals. We analyze the electronic structure, spin magnetic moments, and spin density of $$\alpha $$ α -Al$$_{2}$$ 2 O$$_{3}$$ 3 as a function of both dopant species (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu) and depth using first principles calculations. Our results show that all dopants, with the exception of Sc, produce magnetic moments that are concentrated to the surface of alumina with varying degrees of delocalization. It is seen that all of the dopants are at least meta-stable on the surface and must overcome an energy barrier of 0.19–1.14 eV in order to diffuse from the surface into the bulk. As a result of judiciously doping with select 3d transition metals the surface of alumina can be made magnetic. This could lead to novel applications in data storage, catalysis, and biomedical engineering through an added surface functionality.