Effect Of Magnetocrystalline Anisotropy Research Articles

Spin dynamics investigation and structural analysis of ambient scalable Sr2+ doped zirconium ferrite nanoparticles synthesized by low temperature auto combustion route

Microwave spin resonance behaviour of Sr2+ doped Zirconium ferrite Zr1-xSrxFe2O4; (0 ≤ x ≥ 0.20) nanoparticles synthesized by auto combustion route has been investigated by electron paramagnetic resonance (EPR) which show a broad ferromagnetic resonance signal with a superimposed hump signal which is attributed to ferrite Fe3+ ions and oxygen vacancies which is in agreement with XRD and XPS. EPR shows low spin concentration and smaller relaxation time for Zr0.80Sr0.20Fe2O4 which can be used for hyperthermia and for use as a MRI contrast agent. EDS and XPS confirms the presence of Zr, Sr, Fe, O, and C and HRTEM images confirm growth along (220) and (311) with an interatomic distance of 0.3327 nm and 0.2622 nm respectively, thus, authenticating the formation of spinel structure in agreement with FTIR studies. The magnetic behaviour (M − H loop) shows high saturation magnetization and higher value of effective magnetocrystalline anisotropy (Keff) for Zr0.80Sr0.20Fe2O4.

Obtaining extremely low coercivity of high Bs FeCoBSiCPCu nanocrystalline alloys through modulation of magnetic anisotropy

Longitudinal magnetic field annealing is utilized for modifying the magnetic anisotropy and enhancing the magnetic softness of Fe75Co8(B10Si3C3P1)1-x/17Cux (x = 0.5, 0.75, 1, 1.25) nanocrystalline alloys. All of the magnetic field-annealed nanocrystalline alloys with Cu content more than 0.5 at.% exhibit significantly improved soft-magnetic properties, including high saturation magnetic flux density up to 1.87 T, effective permeability of 13,000–16,000 under the condition of 1 A/m and 1 kHz, coercivity as low as 1.6 A/m, and core loss of 0.11–0.45 W/kg under the condition of 1.0 T and 50 Hz. The application of a magnetic field promotes the nucleation and inhibits the growth of grains, leading to an increase in the number density of nanocrystals and the crystalline volume fraction, and a reduction in the grain size. The magnetic field annealing reduces the effective magneto-crystalline anisotropy energy to 2–4 J/m3, and induces longitudinal magnetic anisotropy with anisotropy energy density of 400–900 J/m3 which shows dependence on the crystalline volume fraction. The field-induced magnetic anisotropy dominates over the random local magnetic anisotropies, and results in the formation of regular magnetic domains aligned longitudinally, pinning-free domain wall displacement, and thus enhanced soft-magnetic properties.

Non-stoichiometric ErFe2Mnx compounds: Structure, magnetic, magnetoelastic and magnetothermal properties

Crystal structure, magnetostriction, magnetic and magnetothermal properties have been studied for novel non-stoichiometric ErFe2Mnx (0 ≤ x ≤ 0.6) compounds. It has been found that for х ≤ 0.4 the compounds crystallize with MgCu2-type structure. Curie temperature and magnetic moment values decrease with manganese alloying. Molecular field coefficients have been calculated within ferrimagnetic two-sublattice molecular field model. Magnetic and heat capacity measurements have been used to calculate magnetocaloric effect in a wide temperature range. It has been demonstrated that increasing the Mn content in ErFe2Mnx leads to a significant increase (up to 39 %) of anisotropic magnetostriction value at 77 K in magnetic field of 18 kOe. At the same time, the value of effective magnetocrystalline anisotropy decreases. Thus, manganese alloying opens new way for tuning magnetocrystalline anisotropy and magnetostriction in Laves phase compounds.

Electron spin resonance and induction heating studies of zinc substituted (Mn, Co) ferrite nanoparticles for potential magnetic hyperthermia applications

This study presents an investigation on the various spin relaxation processes taking place at X-Band microwave energy in Zn substituted MnFe2O4 and CoFe2O4 and their induction heating studies. The material properties of these citric acid assisted sol-gel synthesized nanoparticles have been explored using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscope, Vibrating sample magnetometer (VSM) and Electron spin resonance spectroscopy. XRD and Rietveld refinement confirm the face centered cubic spinel structure of the synthesized samples, which is further supported by the observation of absorption bands characteristic of the spinel ferrites in the FTIR spectra. The remanence, coercivity and effective magnetocrystalline anisotropy values from VSM studies show lower value with zinc substitution which is desirable for biomedical application. Various spin resonance parameters like gyromagnetic ratio, peak to peak linewidth, resonance field, spin-lattice and spin-spin relaxation times have been calculated. The induction heating studies of the samples in an alternating magnetic field have been carried out using a field strength of 4.58 × 109 Am-1s-1. All the investigated MNPs are able to raise the temperature to the therapeutic limit of 42–45 °C. The specific absorption rate (SAR) which describe the heating potential of the MNPs is calculated using four different concentrations of each sample - 5 mg mL-1, 10 mg mL-1, 15 mg mL-1 and 20 mg mL-1. SAR values are found to decrease with increase in concentration and achieve the highest value of 303 W/g for Co0.5Zn0.5Fe2O4 nanoparticles with 5 mg mL-1 concentration. The ability of the MNPs to give rise to the therapeutic temperature points toward their suitability as an effective heat mediator in magnetic hyperthermia treatment of cancer.

Effect of seed layers on the static and dynamic magnetic properties of CoIr films with negative effective magnetocrystalline anisotropy

The c-axis oriented hcp-Co81Ir19 magnetic films were prepared on different seed layers (Ni, Cu, Ir, Pt, Au, and No seed). We systematically investigated the impact that surface-free energy and strain energy have on the orientation and defects and/or internal stress of the grains by increasing the lattice mismatch ratio. Moreover, the initial permeability and the natural resonance frequency were discussed in great detail using a comparison between calculated values and experimental values. We found that the almost unchanged 4πM s and μ i are not affected, while the changed H c, intrinsic K grain, and f r are strongly dependent on the seed layer and seed layer material. Moreover, the extracted damping constant is sensitive to the defects and/or internal stress and orientation of the grains. Therefore, the soft magnetic properties and microwave properties are adjusted and optimized by seed layers with different materials.

Rare earth substituted lithium ferrite/carbon black ceramic composites for shielding electromagnetic radiation

The requirement for electromagnetic interference (EMI) shielding materials have been increased in the last few years due to the extensive usage of portable communication/wireless devices. These devices radiate harmful electromagnetic waves; hence it is imperative to explore suitable materials to protect human health from the radiation. In this study, Dy substituted lithium ferrite/carbon black (LiFe5-xDyxO8/CB) composites have been developed for better shielding efficiency. The effect of Dy on structural, microstructural, and magnetic responses is studied systematically. The fluctuations in the lattice constant are attributed to the differences in the ionic radius of Dy and Fe. The addition of Dy caused the inhibition of grain growth and the formation of irregular grains. The saturation magnetization is also enhanced with an increase in Dy concentration up to x = 0.1 (LD10FO/CB) and then decreased after that Neels’ sublattice model interprets the variation in magnetization and the effective magneto crystalline anisotropy is analyzed. The EMI shielding effectiveness (SE) due to absorption and the reflection is enhanced by incorporating Dy (in the X- and Ku- bands). A maximum SE of 26 dB is observed for x = 0.1 compositions. It is noticed that absorption is the dominant mechanism rather than reflection. The highest absorption coefficient (Aeff) of 99.6% is achieved for LD10FO/CB in the range of 17–18 GHz. The values of complex permittivity and permeability for LD10FO/CB are in the range of (20–40) and (2–6), respectively. The incorporation of Dy (rare earth ion) in spinel ferrite led to promote 4f − 3d coupling along with 3d − 3d, which helped to enhance the magnetic and electrical properties. The results demonstrate that such ceramics can be used as a commercial microwave absorber.

Competing magnetic interactions driven tuning of spin-flop field and anomalous thermal expansion in MnTi1−xMnxO3

Multiferroic MnTiO3 (MTO) is made up of alternate Mn2+ (3d5) and Ti4+ (3d0) layers along the c-axis. It undergoes a magnetic spin-flop driven ferroelectric polarization flop beyond ∼6 T below TN∼64 K. MTO also exhibits a weak negative thermal expansion along the c-axis below ∼90 K. We demonstrate that doping Mn ions at non-magnetic Ti layers acts as a very effective microscopic control parameter to systematically tune both these functional responses. Tuning of c/a lattice parameters in MnTi1−xMnxO3 leads to significant reduction in the spin-flop critical magnetic field from ∼6 T to more easily accessible fields (<2 T for x=0.05). Simultaneously, the controlled tuning of magnetic frustration due to Mn-doping at Ti sites also helps in a systematic enhancement of anomalous thermal expansion in regard to increasing the onset temperature for anomalous expansion to higher values (by ∼40 K for x=0.10) and also strengthening its magnitude (by ∼30% at 15 K for x=0.10 in comparison to x=0.00). Increase in the c/a ratio with Mn doping in MnTiO3 likely causes reduction in the effective magnetocrystalline anisotropy, which leads to a decrease in the value of the spin-flop magnetic field. Detailed temperature-dependent structural analyses shed light on the critical role of exchange striction mechanism in tuning the negative thermal expansion in doped MnTiO3.

Co substituted Ni–Zn ferrites with tunable dielectric and magnetic response for high-frequency applications

Microwave ferrites are the most promising materials for high frequency and high-power devices. In this work, Co substituted Ni–Zn ferrites (Ni0.5-xZn0.5CoxFe2O4; x = 0–0.4) are synthesized, and the structural, morphology, dielectric, magnetic response are systematically investigated. The X-ray diffraction pattern (XRD) pattern confirmed the formation of pristine cubic phase alone without any secondary phase in all the samples. Substitution of Co2+ resulted in increased crystallite size and lattice constant. Raman peak intensity is suppressed, and a shift towards a lower wavenumber is observed with Co substitution. The change in position and intensity is analyzed and attributed to the change in cationic distribution in tetrahedral and octahedral positions by deconvoluting the Raman peaks. The Energy-dispersive X-ray spectroscopy (EDAX) analysis confirms the stoichiometry of compounds. The real permittivity and tan δ are decreased with the dilution of Co (x = 0: ε' = 24, tan δ = 0.015; x = 0.4: ε' = 11, tan δ = 0.035 @ 1 MHz). Further, permeability initially increased in the X band frequency range and decreased with increasing Co concentration. An increase in the saturation magnetization was observed initially with increased Co content and a decrease after x = 0.2. A maximum saturation magnetization (Ms = 63.3 emu/g) observed for x = 0.2 composition. Interestingly, a giant coercivity and high effective magnetocrystalline anisotropy are observed with the incorporation of Co at low temperatures (5 K). The low dielectric loss, high saturation magnetization, and low coercivity at room temperature of Co substituted Ni–Zn ferrites suggest that these compounds are potential candidates for high-frequency devices (circulators).

Effect of magnetocrystalline anisotropy on magnetocaloric properties of an AlFe2B2 compound

It is well known that the temperature dependence of the effective magnetocrystalline anisotropy energy obeys the $l(l+1)/2$ power law of magnetization in the Callen-Callen theory. Therefore, according to the Callen-Callen theory, the magnetocrystalline anisotropy energy is assumed to be zero at the critical temperature where the magnetization is approximately zero. This study estimates the temperature dependence of the magnetocrystalline anisotropy energy by integrating the magnetization versus magnetic field ($M\ensuremath{-}H$) curves, and found that the magnetocrystalline anisotropy is still finite even above the Curie temperature in the uniaxial anisotropy, whereas this does not appear in the cubic anisotropy case. The origin is the fast reduction of the anisotropy field, which is the magnetic field required to saturate the magnetization along the hard axis, in the case of cubic anisotropy. Therefore, the magnetization anisotropy and anisotropic magnetic susceptibility, which are the key factors of magnetic anisotropy, could not be established in the case of cubic anisotropy. In addition, the effect of magnetocrystalline anisotropy on magnetocaloric properties, as the difference between the entropy change curves of ${\mathrm{AlFe}}_{2}{\mathrm{B}}_{2}$ appears above the Curie temperature, is in good agreement with a previous experimental study. This is proof of magnetic anisotropy at slightly above Curie temperature.

Temperature-dependent out-of-plane anisotropy in compressively strained La0.67Sr0.33MnO3 thin films

We studied the temperature and strain dependence of the perpendicular magnetic anisotropy in La0.67Sr0.33MnO3 thin films by performing temperature- and angle-dependent magnetotransport measurements. Three films of similar thickness (14 u.c., 14 u.c. and 15 u.c.) but with different out-of-plane crystallographic strain (1.9%, 0.9% and -0.7%) are studied. The films are grown on LaAlO3 and SrTiO3 substrates by pulsed laser deposition. We observe a clear increase in the out-of-plane magnetic anisotropy with increasing out-of-plane strain in the angle-dependent magnetotransport measurements which is present up to 80 K for the highest (1.9%) strained sample. The deformation of the unit cell, as discussed in earlier reports, point to the magnetocrystalline anisotropy as the main driver altering the magnetic easy axis direction. Our results highlight the utility of the effective magnetocrystalline anisotropy as a tool to control the desired anisotropy in crystalline thin films of La0.67Sr0.33MnO3.

Impact of In3+ cations on structure and electromagnetic state of M−type hexaferrites

The solid solutions of In3+ doped M−type strontium hexaferrites were produced using a conventional solid-state reaction method, and Rietveld analysis of the neutron diffraction patterns was conducted. In3+ cations occupy octahedral (4fVI and 12 k) and tetrahedral (4fIV) positions (SG = P63/mmc (No.194)). The average particle size is 837–650 nm. Curie tempearature (TC) of the compounds monotonically decreased down to ∼ 520 K with increasing x. A frustrated magnetic state was detected from ZFC and FC magnetizations. saturation magnetization (Ms) and effective magnetocrystalline anisotropy coefficient (keff) were determined using the law of approach to saturation. A real permittivity (ε/) maximum of ∼ 3.3 at ∼ 45.5 GHz and an imaginary permittivity (ε//) of ∼ 1.6 at ∼ 42.3 GHz were observed for x = 0.1. A real permeability (μ/) maximum of ∼ 1.5 at ∼ 36.2 GHz was observed for x = 0. A μ// imaginary permeability maximum of ∼ 0.8 at ∼ 38.3 GHz was observed for x = 0.1. The interpretation of the results is based on the type of dielectric polarization and the natural ferromagnetic resonance features.

Features of structure, magnetic state and electrodynamic performance of SrFe12\u2212xInxO19

Indium-substituted strontium hexaferrites were prepared by the conventional solid-phase reaction method. Neutron diffraction patterns were obtained at room temperature and analyzed using the Rietveld methods. A linear dependence of the unit cell parameters is found. In3+ cations are located mainly in octahedral positions of 4fVI and 12 k. The average crystallite size varies within 0.84–0.65 μm. With increasing substitution, the TC Curie temperature decreases monotonically down to ~ 520 K. ZFC and FC measurements showed a frustrated state. Upon substitution, the average and maximum sizes of ferrimagnetic clusters change in the opposite direction. The Mr remanent magnetization decreases down to ~ 20.2 emu/g at room temperature. The Ms spontaneous magnetization and the keff effective magnetocrystalline anisotropy constant are determined. With increasing substitution, the maximum of the ε/ real part of permittivity decreases in magnitude from ~ 3.3 to ~ 1.9 and shifts towards low frequencies from ~ 45.5 GHz to ~ 37.4 GHz. The maximum of the tg(α) dielectric loss tangent decreases from ~ 1.0 to ~ 0.7 and shifts towards low frequencies from ~ 40.6 GHz to ~ 37.3 GHz. The low-frequency maximum of the μ/ real part of permeability decreases from ~ 1.8 to ~ 0.9 and slightly shifts towards high frequencies up to ~ 34.7 GHz. The maximum of the tg(δ) magnetic loss tangent decreases from ~ 0.7 to ~ 0.5 and shifts slightly towards low frequencies from ~ 40.5 GHz to ~ 37.7 GHz. The discussion of microwave properties is based on the saturation magnetization, natural ferromagnetic resonance and dielectric polarization types.

Micromagnetic study for optimum performance of isotropic Nd2Fe14B/α-Fe nanocomposite bulk magnets

The nanocomposite magnets attract great interest in the study of high-performance magnets. Here, the micromagnetic simulations have been performed to investigate the effects of various microstructural factors such as grain geometry, grain size, and volume fraction on the performance of a soft-in-hard-matrix nanostructured Nd2Fe14B/α-Fe isotropic magnet. It is found that there is very little dependence of remanence on the geometry of the soft phase. The coercivity decreases with increasing the soft grain size, whereas it has a variation tendency depending on the size of hard grain size. In contrast to a significant role of soft-sphere geometry in anisotropic nanocomposites (Skomski et al 2013 IEEE Trans. Magn. 49 3215), the energy product of the soft-sphere system simulated here is slightly increased (8 kJ m−3), compared with that of the soft-cylinder system. In the meantime, a significant enhancement in energy product with increasing the soft grain size is observed only when the hard grain size is less than 15 nm. Our simulation predicts the highest energy product of 347 kJ m−3 with a hard grain size of 5 nm and a soft-sphere size of 12.4 nm (30 vol% of the soft phase). It is shown that the effective magnetocrystalline anisotropy is responsible for the variation in coercivity, based on its quantitative evaluation for the soft-sphere system.

Superspinglass state in functionalized zeolite 5A-maghemite nanoparticles

The structural, vibrational, and magnetic properties of maghemite nanoparticles functionalized with zeolite type 5A and synthesized by coprecipitation were studied in detail. Crystallite and particle sizes were determined and discussed based on the polydispersity index. Its value of 0.4 has suggested the presence of a broad particle distribution with particle sizes between 3 and 20 nm. Three samples were successfully functionalized either before or after the formation of the maghemite nanoparticles. Infrared studies have shown that the functionalization has occurred by hydrated surface groups present in the zeolite type 5A surface, which have favored strong bindings and highly concentrated regions of maghemite nanoparticles. From the temperature dependence of the hyperfine magnetic field obtained by Mössbauer spectroscopy, the effective magnetocrystalline anisotropy constants of the three nanohybrids were determined. They are one order of magnitude higher than for the bulk counterpart, and there is evidence for strong interparticle interactions for the three studied nanohybrids. These strong magnetic interactions of the nanoparticles in the zeolite framework have favored a superspinglass-like behavior for all samples with transition temperatures located at 74 and 208 K, as confirmed by AC susceptibility measurements.

Local inspection of magnetic properties in GdMnIn by measuring hyperfine interactions

GdMnIn is reported to crystallize in the hexagonal MgNi2-type structure presenting a spin-glass behavior with no magnetic order attributed to the triangular spin frustration of magnetic ions. In the present work, FC-ZFC magnetization, specific heat and AC susceptibility measurements along with the local magnetic exchange measured by hyperfine interactions at In sites are used to investigate the magnetic behavior in GdMnIn compound. The ZFC-FC magnetization curves exhibit an inflection which was ascribed to the antiferromagnetic transition at TN= 145 K. These curves also give an indication of thermomagnetic irreversibility at 118 K, which along with the absence of inflection in specific heat results might be associated to spin-glass behavior. Results of AC susceptibility and magnetic hyperfine field measured using 111In(111Cd) probe nuclei carried out by perturbed angular correlations (PAC) technique did not show evidence of spin-glass behavior. The thermomagnetic irreversibility in FC-ZFC curves along with results of hyerfine interactions suggest the presence of magneto-crystalline anisotropy effects and a weak long-range coupling in GdMnIn.

Theoretical study on the magnetic anisotropy of monolayer iron from Orbital Selective External Potential calculations

Magnetocrystalline anisotropy energy is the core concern in the field of magnetic storage theory. This study explored the theoretical mechanism of magnetocrystalline anisotropy energy of monolayer iron with the change of strain by using an Orbital Selective External Potential (OSEP) method. It is found that magnetocrystalline anisotropy energy of monolayer iron changes linearly with the strain through first principles calculation. We predict the contribution of 3 d z 2 orbital using matrix-analysis. Particularly, we utilize the Orbital Selective External Potential to shift the energy levels of 3 d orbitals, observing the occupation number influence on magnetocrystalline anisotropy energy. As a result, we confirmed the main contribution of 3 d z 2 orbital. It is the first application of OSEP method in solving the strain effect of magnetocrystalline anisotropy in 3 d ferromagnet systems. This research will help understand the theoretical mechanism of magnetic memory devices based on spintronics. • We believe the paper may be of particular interest to the readers as it introduced Orbital Selective External Potential to study the magnetocrystalline anisotropy energy (MAE) of monolayer iron. • A so-called “Orbital Selective External Potential” (OSEP) method is used to quantitatively move 3 d orbital energy levels and thus determine the main contribution of 3 d z 2 orbital in linear variation of MAE with strain. • The result agrees with the matrix-analysis, which proves that OSEP can precisely determine the contribution of a unique orbital.

The magnetoelastic properties of laves-phase TbxHo0.9-xNd0.1Fe1.8Mn0.1 compounds: An in-situ Lorentz microscope study

Abstract Magnetocrystalline anisotropy and magnetic field-driven magnetic domain movement have significant influences on magnetoelastic properties. In this work, polycrystalline TbxHo0.9-xNd0.1Fe1.8Mn0.1 (0.08 ≤ x ≤ 0.25) compounds were prepared and the characteristics of these compounds were then investigated, i.e. magnetic domain walls, magnetocrystalline anisotropy compensation and magnetostriction. The experimental results suggest that the easy magnetisation direction (EMD) lies towards the axis for x ≤ 0.08 and the axis for x ≥ 0.15. The EMD is further confirmed, for the first time, by an electron holography (EH) technique. Additionally, the relationship between the difficulty of domain walls motion and the magnitude of magnetocrystalline anisotropy was investigated by in-situ Lorentz transmission electron microscopy (LTEM). For the Tb0.15Ho0.75Nd0.1Fe1.8Mn0.1 compound, a large low-field induced magnetostriction, e.g. λa ∼ 322 ppm at 2 kOe, was obtained. This work can help to understand the effects of magnetocrystalline anisotropy on magnetostrictive properties for the rare earth-transition metal Lave-phase materials.

Magnetization states driven by spin-transfer torque in spin-valve nanopillars in presence of four-fold magnetocrystalline anisotropy

In this work, the magnetization states under the spin-transfer switching effect are investigated in a nanopillar device composed of a half-metallic Heusler Co1.5Fe1.5Ge alloy with a four-fold in-plane magnetocrystalline anisotropy. A comparative study with a half-metallic Heusler alloy of Co2FeAl0.5Si0.5 and a typical material of Fe is realized by numerically solving the Landau-Lifshitz-Gilbert (LLG) equation with the Spin-Transfer Torque (STT) contribution, using micromagnetic simulations. Our ultimate goal is to elucidate the origins of the intermediate state (IS) that occurs during magnetization switching by deeply examining the effects of magnetocrystalline anisotropy and shape anisotropy on the magnetization states through analyzing and comparing various switching processes. Our simulation results showed that the magnetization switching via a single-step under low current densities is possible at certain critical cross-sectional dimensions of the ellipse that are adjusted to increase the demagnetization field against the four-fold in-plane magnetocrystalline anisotropy. As well, we provided in this paper a set of appropriate geometric dimensions which allow the magnetization to reverse via a single-step by overcoming IS with minimal spin-polarized current densities.

Synthesis of cobalt ferrite colloidal nanoparticle clusters by ultrasonic-assisted solvothermal process

In the present work, cobalt ferrite colloidal nanoparticle clusters were synthesized via solvothermal method using cobalt and iron chlorides, sodium acetate, and ethylene glycol as starting materials. The effects of ultrasonication process of the primary solution on the structure, microstructure, specific surface area, and molecular and magnetic characteristics of the synthesized powders were investigated. Results showed that solvothermal method with/without ultrasonication resulted in nanoscale cobalt ferrite clusters. Field emission scanning electron microscopy micrographs revealed that the synthesized powders were consisted of well-dispersed raspberry-like clusters. Applied ultrasonic waves decreased the mean cluster size while increased the cluster dispersion. The synthesized cobalt ferrite powders had high specific surface area of about 127 m2g−1 which slightly decreased to about 122 m2g−1 after ultrasonication. Generally, the powders showed superparamagnetic properties with a minimum saturation magnetization of 55 emu/g. Ultrasonication for 60 min reduced the coercivity and the effective magneto-crystalline anisotropy of the cobalt ferrite powders.

Tuning the magnetocrystalline anisotropy and spin dynamics in CoxZn1-xFe2O4 (0 ≤ x ≤ 1) nanoferrites

Abstract The present work investigates the static and dynamic magnetization behaviour of Co-Zn nanoferrites and optimizes the magnetocrystalline anisotropy and spin relaxation time. The CoxZn1-xFe2O4 (0 ≤ x ≤ 1) magnetic nanoparticles are synthesized by pH-controlled co-precipitation method. The Le Bail structural refinement of X-ray diffraction patterns confirms the single phase formation with negligible synthesis dependent site inversion. The room temperature static dc magnetization study shows a continuous transition from hard ferrimagnetic CoFe2O4 to soft and weakly magnetic ZnFe2O4, which has been successfully explained with Yafet-Kittel model. Furthermore, approach-to-saturation analysis gives effective magnetocrystalline anisotropy of 1.45 × 104 J/m3 and lowest anisotropy field of 1.3 kOe for x = 0.4. Next, the dynamic magnetization is studied with Electron Spin Resonance spectroscopy. The lineshape analysis gives highest g-value of 3.88 and lowest spin-relaxation time (T2) of 4.86 × 10−12 s for x = 0.4, which is in agreement with static magnetization study. The optimized magnetocrystalline anisotropy and lowest spin-relaxation time for Zn0.4Co0.6Fe2O4 make it a good candidate for use in different biomedical applications.