Torque Magnetometry Research Articles

Osmium(III) Acetylacetonate and Its Missing Polymorph: A Magnetic and Structural Investigation.

Despite the potential for their application, the magnetic behavior of complexes containing 4d and 5d metal ions is underexplored, evidencing the need for benchmark multi-technique studies on simple molecules. We report here a structural and magnetic study on osmium(III) acetylacetonate [Os(acac)3]. X-ray single crystal diffraction did not allow us to determine the structure of the β-polymorph of [Os(acac)3]. The combined magnetic (dc magnetic measurements on powder and cantilever torque magnetometry on single crystal) and spectroscopic (electron paramagnetic resonance, EPR) characterization is here used to provide further evidence that its structure is indeed the one of the orthorhombic "missing polymorph", analogous to the ruthenium(III) derivative. Our study shows that all acetylacetonate complexes of the eighth group of the periodic table show dimorphism and are isomorphic. The EPR characterization allowed the experimental assessment of the easy axis nature of the ground doublet and the determination of the first hyperfine coupling in an osmium complex. Torque magnetometry, applied here for the first time on an osmium-based molecule, determined the orientation of the easy axis along the pseudo C3 axis of the complex. Ac magnetometric measurements revealed in-field slow relaxation of the magnetization further slowed by the suppression of dipolar fields via magnetic dilution in the isostructural gallium(III) analogue.

Anisotropic quantum transport in ZrSiS probed by high-field torque magnetometry

Anisotropic quantum transport in ZrSiS probed by high-field torque magnetometry

Rashba-splitting-induced topological flat band detected by anomalous resistance oscillations beyond the quantum limit in ZrTe5

Topological flat bands — where the kinetic energy of electrons is quenched — provide a platform for investigating the topological properties of correlated systems. Here, we report the observation of a topological flat band formed by polar-distortion-assisted Rashba splitting in the three-dimensional Dirac material ZrTe5. The polar distortion and resulting Rashba splitting on the band are directly detected by torque magnetometry and the anomalous Hall effect, respectively. The local symmetry breaking further flattens the band, on which we observe resistance oscillations beyond the quantum limit. These oscillations follow the temperature dependence of the Lifshitz–Kosevich formula but are evenly distributed in B instead of 1/B at high magnetic fields. Furthermore, the cyclotron mass gets anomalously enhanced about 102 times at fields ~ 20 T. Our results provide an intrinsic platform without invoking moiré or order-stacking engineering, which opens the door for studying topologically correlated phenomena beyond two dimensions.

Evidence for unfolded Fermi surfaces in the charge-density-wave state of kagome metal FeGe revealed by de Haas–van Alphen effect

The antiferromagnetic kagome lattice compound FeGe has been revealed to host an emergent charge-density-wave (CDW) state which manifests complex interplay between the spin, charge, and lattice degrees of freedom. Here, we present a comprehensive study of the de Haas–van Alphen effect by measuring torque magnetometry under magnetic fields up to 45.2 T to map Fermi surfaces in this unusual CDW state. For a field along the c direction, we resolve four cyclotron orbits, with the largest one roughly corresponding to the area of the 2×2 folded Brillouin zone. Three smaller orbits are characterized by light effective cyclotron masses in the range of (0.18–0.30)me. Angle-resolved measurements identify one Fermi surface segment with weak anisotropy. Combined with band structure calculations, our results suggest that features of unfolded Fermi surfaces are robust against CDW reconstruction, corroborating the unconventional effect of a short-ranged CDW on the electronic structure. Published by the American Physical Society 2024

The effect of second coordination sphere interactions on the magnetic anisotropy of transition metals.

In the study of mononuclear transition metal single molecule magnets (SMMs), extensive research has concentrated on identifying optimal coordination geometries around the central metal ion to enhance SMM properties. However, the role of non-covalent interactions in the second coordination sphere has been relatively underexplored. Here, we study the impact of non-covalent Cl⋯H interactions on the magnetic anisotropy of the central Co(II) ion in the distorted axially compressed octahedral complex CoCl2(tu)4 (1) (tu = SC(NH2)2). By performing cantilever torque magnetometry on 1, the orientation of the magnetic easy axis is found to deviate by almost 40° from the axial Co-Cl bond. Theoretical modelling on structural modifications of the structure of 1, quantifies how the distance between the Cl ligand and the nearest H-atom significantly influences the orientation of the magnetic easy axis and the D-value. Experimental chemical bonding analysis based on multipole modelling of synchrotron X-ray diffraction data on 1 reveal that the nearby H-atoms polarize the electron density of the Cl-ligands. This polarization results in reduced electron density at the axial positions on the Co octahedra, explaining the calculated increase in the magnitude of the D-value, when the H-atoms are moved away from Cl in silico. Topological analysis of theoretical electron densities on modified structures of 1 corroborates an increase in the electron density at the Co-Cl bond critical point, as the nearby H-atoms are moved further from Cl. These findings demonstrate the significant influence that non-covalent interactions have on the magnetic anisotropy of mononuclear transition metals and opens the possibility of utilizing these interactions in the design of transition metal based SMMs.

Superconducting Precursors in Bi/Pb Multiphase Cuprates Fabricated by the Solar Technology and their Comparative Study by Torque Magnetometry Methods

A special method has been applied to synthesize HTSC samples of Bi1.7Pb0.3Sr2Ca(n-1)CunOy with increased local inhomogeneities, using solar energy for the melting and following superfast quenching of the melt (SFAQ-T technology). This study carried out a comparative analysis using low-frequency torsional vibration and resonant vibrating reed spectroscopy methods. The results showed a possibility for the existence of high-temperature superconducting precursors with Tc = 107-138 K and the potential advantages of the application of the resonant vibrating reed method.

Intrinsic pinning of FeSe1−xSx single crystals probed by torque magnetometry

Intrinsic pinning is caused by natural pinning centers that occur because of the modulation of the order parameter or weak superconducting layers. Early work has shown that intrinsic pinning generates a high pinning force and critical current density in some layered oxide superconductors. Studying the intrinsic pinning of superconductors is crucial for both fundamental studies and potential applications. Herein, we use torque magnetometry to study angle-resolved in-plane and out-of-plane magnetic torque for a series of high-quality FeSe1−xSx single crystals. A fourfold torque signal was observed when the magnetic field was within the ab plane. We interpret that this fourfold in-plane irreversible torque is from the intrinsic pinning due to combined effects of gap nodes/minimum and twin domains. Additionally, we attributed the observed out-of-plane torque peaks to intrinsic pinning due to the layered structure.

The in- and out-of-plane magnetisation of highly underdoped YBa2Cu3O6+x single crystals

Previously we have shown how measurements of static magnetic susceptibility χc(T) of YBa2Cu3O6+x single crystals for magnetic fields applied along the c-axis, and χab(T) for fields in the ab-plane, can give useful information about their thermodynamic properties which are still being hotly debated. SQUID magnetometry above the superconducting (s/c) transition temperature Tc is used for larger crystals, while piezolever torque magnetometry gives χc(T)-χab(T) for tiny crystals. Here we present new data for more heavily under-doped crystals with hole concentrations per CuO2 plane, p =0.058 to 0.073. We again find that the T-dependent anisotropy well above Tc arises from the pseudogap and the g-factor anisotropy, while at lower T there are Gaussian s/c fluctuations with a strong cut-off. This is possibly a different region where neutron scattering studies give evidence for competition between incommensurate magnetic short-range order and superconductivity. We have studied crystals with three values of x, measuring χc(T) and χab(T) immediately after fixing x by quenching on to a copper block and again after allowing sufficient time at room temperature for the Cu-O chains to order. Thus, we report data for three pairs of underdoped (UD) crystals with Tc ranging from 13 to 36 K, namely UD13 and UD20, UD15 and UD30, UD23 and UD36. As found previously for polycrystalline samples, ordering the Cu-O chains increases Tc and substantially reduces the Curie term. These are isotropic, in contrast to the Pauli-like susceptibility from the CuO2 planes where there is g factor anisotropy, and this allows us to make a powerful novel analysis. At higher T, χc(T)- χab(T) varies as a + bT where the bT term arises from the pseudogap. At lower T, deviations from this behaviour are analysed in terms of 2D or 3D Gaussian s/c fluctuations to obtain in-plane coherence lengths and upper critical fields as T→0.

High quantum oscillation frequencies and nontrivial topology in kagome superconductor KV3Sb5 probed by torque magnetometry up to 45 T

Here, we present the Fermi surface properties of the kagome superconductor ${\mathrm{KV}}_{3}{\mathrm{Sb}}_{5}$ using torque magnetometry at applied fields up to 45 T and temperatures down to that of liquid $^{3}\mathrm{He}$ (0.32 K). The torque signal shows clear de Haas--van Alphen (dHvA) oscillations with 14 major frequencies ranging from $\ensuremath{\sim}33$ to 2149 T, nine of which are higher frequencies (above 500 T) that have never been reported in ${\mathrm{KV}}_{3}{\mathrm{Sb}}_{5}$. Angular dependence measurements of the dHvA oscillations were carried out to investigate the dimensionality of the Fermi surface. Based on our analysis, several frequencies follow the $1/\mathrm{cos}\phantom{\rule{0.16em}{0ex}}\ensuremath{\theta}$ dependence, where $\ensuremath{\theta}$ is the tilt angle with respect to the applied field direction and oscillations disappear above $\ensuremath{\theta}={60}^{\ensuremath{\circ}}$, which suggest that Fermi surfaces corresponding to these frequencies are quasitwo dimensional. The Berry phase (${\mathrm{\ensuremath{\Phi}}}_{\mathrm{B}}$), determined by constructing a Landau level fan diagram, was found to be ${\mathrm{\ensuremath{\Phi}}}_{\mathrm{B}}\ensuremath{\sim}\ensuremath{\pi}$, which strongly suggests the nontrivial topology of ${\mathrm{KV}}_{3}{\mathrm{Sb}}_{5}$. To explain the experimental results, we carried out band-structure and Fermi-surface calculations using density functional theory (DFT) for both pristine and charge-density wave (CDW) phases. We found that the Fermi surface undergoes severe reconstruction in the CDW phase and, more importantly, our calculation results are in reasonable agreement with the experimentally measured Fermi-surface frequencies. The observation in this paper of very high quantum oscillation frequencies in ${\mathrm{KV}}_{3}{\mathrm{Sb}}_{5}$ and the determination of their detailed Fermi-surface properties, along with the analyses of corresponding DFT calculation results, are crucial for understanding CDW order, unconventional superconductivity, and nontrivial topology in $A{\mathrm{V}}_{3}{\mathrm{Sb}}_{5}\phantom{\rule{0.28em}{0ex}}(A=\mathrm{K},\mathrm{Rb},$ and Cs), as well as the interplay among them.

Coherent description of the magnetic properties of SeCuO3 versus temperature and magnetic field

We report a combined theoretical and experimental investigation devoted to getting deeper insights into the exotic magnetic properties of the low-dimensional ${\mathrm{SeCuO}}_{3}$ system, for which the two inequivalent Cu(1) and Cu(2) sites show different quantum dynamics. First-principles calculations based on the density functional theory were performed to extract the magnetic exchange couplings. Briefly, we notably find that (i) the magnetic structure can be decomposed into two subsystems made of strongly antiferromagnetically coupled Cu(1) singlet state dimers and weak antiferromagnetic Cu(2) spin chains and (ii) weak ferromagnetic interactions between the two subsystems lead to magnetic frustration. The present model allows us to reproduce both magnetic susceptibility and torque magnetometry measurements. In addition, high-magnetic-field experiments and density-matrix renormalization-group simulations evidence a half-magnetization plateau at 40--45 T associated with the polarization of the Cu(2) spin chains, while the Cu(1) dimers are expected to reach the triplet state at 210--220 T.

Fermi surface mapping of the kagome superconductor RbV3Sb5 using de Haas-van Alphen oscillations

We present the results from torque magnetometry studies of the kagome superconductor ${\mathrm{RbV}}_{3}{\mathrm{Sb}}_{5}$ under applied fields up to 45 T and temperatures down to liquid $^{3}\mathrm{He}$ temperature (0.32 K). The torque signal shows clear de Haas--van Alphen (dHvA) oscillations with eight distinct frequencies ranging from $\ensuremath{\approx}150$ to 3000 T. Among these, five are above 500 T. Angle-dependent measurement of dHvA oscillations shows that all frequencies follow 1/$\mathrm{cos}\ensuremath{\theta}$ dependence, where $\ensuremath{\theta}$ is the tilt angle with respect to the applied field direction, and the oscillations disappear above $\ensuremath{\theta}$ = ${60}^{\ensuremath{\circ}}$, which confirms that the Fermi surfaces corresponding to these frequencies are two dimensional. The Berry phase ($\ensuremath{\phi}$), calculated by constructing a Landau level fan diagram, is found to be $\ensuremath{\approx}\ensuremath{\pi}$, which strongly supports the nontrivial topology of ${\mathrm{RbV}}_{3}{\mathrm{Sb}}_{5}$. Using the Lifshitz-Kosevich formula, we estimate the effective mass (${m}^{*}$) of charge carriers in ${\mathrm{RbV}}_{3}{\mathrm{Sb}}_{5}$, and it is found to be heavier ($\ensuremath{\approx}0.7{m}_{o}$, where ${m}_{o}$ is the free electron mass) than that for other topological insulators. The findings of high frequencies up to 3000 T in ${\mathrm{RbV}}_{3}{\mathrm{Sb}}_{5}$ have not been reported previously, and the results regarding the Fermi surface of ${\mathrm{RbV}}_{3}{\mathrm{Sb}}_{5}$ are crucial for understanding the charge density wave order, superconductivity, and nontrivial topology in $A{\mathrm{V}}_{3}{\mathrm{Sb}}_{5}$ ($A$ = K, Rb, and Cs), as well as the interplay among them.

Magnetic behavior and chaining of strontium ferrite-nylon composite above the melting temperature

To better understand Magnetic Field Assisted Additive Manufacturing (MFAAM) the effect of a magnetic field on the orientation and distribution of magnetic particles in a molten magnetic composite was studied. Vibrating Sample Magnetometer (VSM) measurements were made on Sr-ferrite/PA12 fused deposition modeling filaments of different packing fraction (5 and 40 wt. %). The rotation of the sample’s magnetic moment upon application of a field perpendicular to the easy axis was monitored with a biaxial VSM above the PA12’s softening temperature. The observed magnetic moment transients depend on the temperature, the applied alignment field, the packing fraction, and the initial field-anneal procedure. Longer field-anneals result in larger time constants and seem to induce a hurdle that prevents complete alignment at low temperatures and/or for small fields. Results indicate the molten composite is a non-Newtonian fluid that can support a yielding stress. Scanning Electron microscopy (SEM) images taken on field-annealed samples at 230 °C show strong chaining with little PA-12 left between individual Sr-ferrite particles suggesting that direct particle to particle interaction is the reason for the observed non-zero yielding stress. The melt viscosity of the composite increases with the number of thermal cycles above the melting temperature (Tm). Room temperature (RT) torque magnetometry measurements show that magnetic anisotropy depends on the field annealing process through induced shape anisotropy contributions originating from magnetic particle agglomerates.

Large magnetic anisotropy and magnetostriction in thin films of CoV2O4

Spinel Cobalt Vanadate CoV$_2$O$_4$ has been grown on (001) SrTiO$_3$ substrates. Using torque magnetometry experiments, we find that the previously observed temperature induced anisotropy change, where the easy axis changes from the out of plane [001] direction to a biaxial anisotropy with planar <100> easy axes, occurs in a gradual second-order structural phase transition. This work characterizes this transition and the magnetic anisotropies in the (001), (100), and (-110) rotation planes, and explores their field dependence up to 30~T. Below 80~K, hysteretic features appear around the hard axes, i.e., the out-of-plane direction in (-110) and (010) rotations and the planar <110> directions in (001) rotations. This is due to a Zeeman Energy that originates from the lag of the magnetization with respect to the applied magnetic field as the sample is rotated. The appearance of the hysteresis, which persist up to very high fields, shows that the anisotropy at low temperature is rather strong. Additionally, field dependent distortions to the symmetry of the torque response in increasing applied fields shows that magnetostriction plays a large role in determining the direction and magnitude of the anisotropy.

High-frequency torsional motion transduction using optomechanical coupled oscillators

Using light to measure an object’s motion is central to operating mechanical sensors that probe forces and fields. Cavity optomechanical systems embed mechanical resonators inside optical resonators. This enhances the sensitivity of optomechanical measurements, but only if the mechanical resonator does not spoil the properties of the optical cavity. For example, cavity optomechanical detection of resonators made from optically absorbing materials, or whose geometry does not possess suitable spatial symmetry, is challenging. Here we demonstrate a system that overcomes challenges in measuring high-frequency twisting motion of a nanodisk by converting them to vibrations of a photonic crystal cavity. Optomechanical readout of the cavity then enables measurement of the nanodisk’s torsional resonances with sensitivity 5.1 × 10 − 21 − 1.2 × 10 − 19 N m / H z for a mechanical frequency range of 5–800 MHz. The nanodisk can be outfitted with magnetic nanostructures or metasurfaces without affecting the optical properties of the cavity, making the system suitable for torque magnetometry and structured light sensing.

Fermiology of the Dirac type-II semimetal candidates (Ni,Zr) Te2 using de Haas–van Alphen oscillations

We have investigated the Fermi surface properties of the Dirac type-II semimetal candidates (Ni,Zr)${\mathrm{Te}}_{2}$ using torque magnetometry with applied fields up to 35 T. Magnetization shows clear de Haas--van Alphen (dHvA) oscillations above 20 T. The dHvA oscillations are smooth and well defined and consist of one distinct frequency (${F}_{\ensuremath{\alpha}}\phantom{\rule{4pt}{0ex}}\ensuremath{\sim}530$ T) in $\mathrm{Zr}{\mathrm{Te}}_{2}$ and three (${\overline{F}}_{\ensuremath{\alpha}}\phantom{\rule{4pt}{0ex}}\ensuremath{\sim}72$ T, ${\overline{F}}_{\ensuremath{\beta}}\phantom{\rule{4pt}{0ex}}\ensuremath{\sim}425$ T, and ${\overline{F}}_{\ensuremath{\gamma}}\phantom{\rule{4pt}{0ex}}\ensuremath{\sim}630$ T) in $\mathrm{Ni}{\mathrm{Te}}_{2}$. The Berry phase $\ensuremath{\phi}$ was determined by constructing the Landau level fan diagram. It is found that $\ensuremath{\phi}\phantom{\rule{4pt}{0ex}}\ensuremath{\sim}$ 0 and $\ensuremath{\pi}$ for ${F}_{\ensuremath{\alpha}}$ and ${\overline{F}}_{\ensuremath{\beta}}$, respectively, for $\mathrm{Zr}{\mathrm{Te}}_{2}$ and $\mathrm{Ni}{\mathrm{Te}}_{2}$. This strongly suggests that the Dirac fermions make a dominant contribution to the transport properties of $\mathrm{Ni}{\mathrm{Te}}_{2}$, whereas topologically trivial fermions dominate those in $\mathrm{Zr}{\mathrm{Te}}_{2}$. The presence of lighter effective mass ${m}^{*}=0.13{m}_{e}$ in $\mathrm{Ni}{\mathrm{Te}}_{2}$ compared to ${m}^{*}=0.26{m}_{e}$ in $\mathrm{Zr}{\mathrm{Te}}_{2}$, where ${m}_{e}$ is an electron's rest mass, further confirms the presence of Dirac fermions in $\mathrm{Ni}{\mathrm{Te}}_{2}$. Our density functional theory calculations find that while both systems host type-II Dirac dispersions along the out-of-plane direction, their relative positions and the natures of the dispersions are different. The Dirac cone is closer to the Fermi energy ${E}_{F}$ ($\ensuremath{\sim}100$ meV above) in $\mathrm{Ni}{\mathrm{Te}}_{2}$, whereas it is far ($\ensuremath{\sim}500$ meV) above ${E}_{F}$ for $\mathrm{Zr}{\mathrm{Te}}_{2}$. This is consistent with our experimental finding of a nontrivial Berry phase and dominant contribution from lighter electrons in the quantum oscillation signal for only $\mathrm{Ni}{\mathrm{Te}}_{2}$. These findings suggest that the proximity of the Dirac cone to ${E}_{F}$ in topological compounds is crucial for observing the effect from Dirac quasiparticles in their electrical transport or magnetic properties.

Exchange-induced spin polarization in a single magnetic molecule junction

Many spintronic devices rely on the presence of spin-polarized currents at zero magnetic field. This is often obtained by spin exchange-bias, where an element with long-range magnetic order creates magnetized states and displaces the hysteresis loop. Here we demonstrate that exchange-split spin states are observable and usable in the smallest conceivable unit: a single magnetic molecule. We use a redox-active porphyrin as a transport channel, coordinating a dysprosium-based single-molecule-magnet inside a graphene nano-gap. Single-molecule transport in magnetic field reveals the existence of exchange-split channels with different spin-polarizations that depend strongly on the field orientation, and comparison with the diamagnetic isostructural compound and milikelvin torque magnetometry unravels the role of the single-molecule anisotropy and the molecular orientation. These results open a path to using spin-exchange in molecular electronics, and offer a method to quantify the internal spin structure of single molecules in multiple oxidation states.

Rapid assessment of REBCO CC angular critical current density J c(B, T = 4.2 K, θ) using torque magnetometry up to at least 30 tesla

Detailed design of REBa2Cu3O (REBCO)-based magnets ideally relies on knowledge of the full angular and wide temperature range characterization of the critical current of the REBCO coated conductors (CC) at high magnetic fields. In practice, however, obtaining data by the commonly used electrical transport technique is expensive, tedious, and difficult, due to high critical current values that exceed 2000 A for -plane (θ = 90 deg). The conductors are often damaged during angular transport measurements at angles approaching the ab-plane. Therefore, so far, REBCO magnets have been designed without full data sets. Here, we present results for more than twenty samples of CC all made to the same advanced pinning specification produced by SuperPower Inc. For this, we employed torque magnetometry, benchmarking the results to transport measurements mostly made away from ab-plane, finding good agreement with scaling factors ≈1–1.3. What is striking is the huge variety of properties exhibited by the samples, even for CC made recently. Given the huge attention now being paid to the effects of screening currents and to the torques generated by offsets between the tape plane and the local magnetic field vector, our data set suggests some caution in detailed design of such magnets without having data of the type presented here.

Investigation of the monopole magneto-chemical potential in spin ices using capacitive torque magnetometry

The single-ion anisotropy and magnetic interactions in spin-ice systems give rise to unusual non-collinear spin textures, such as Pauling states and magnetic monopoles. The effective spin correlation strength (Jeff) determines the relative energies of the different spin-ice states. With this work, we display the capability of capacitive torque magnetometry in characterizing the magneto-chemical potential associated with monopole formation. We build a magnetic phase diagram of Ho2Ti2O7, and show that the magneto-chemical potential depends on the spin sublattice (α or β), i.e., the Pauling state, involved in the transition. Monte Carlo simulations using the dipolar-spin-ice Hamiltonian support our findings of a sublattice-dependent magneto-chemical potential, but the model underestimates the Jeff for the β-sublattice. Additional simulations, including next-nearest neighbor interactions (J2), show that long-range exchange terms in the Hamiltonian are needed to describe the measurements. This demonstrates that torque magnetometry provides a sensitive test for Jeff and the spin-spin interactions that contribute to it.

Magnetoresistance oscillation study of the spin counterflow half-quantum vortex in doubly connected mesoscopic superconducting cylinders of Sr2RuO4

Vortices in an unconventional superconductor are an important subject for the fundamental study of superconductivity. A spin counterflow half-quantum vortex (HQV) was predicted theoretically for odd-parity, spin-triplet superconductors. Cantilever torque magnetometry measurements revealed previously experimental evidence for HQVs in doubly connected, single-crystal samples of ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$ with a mesoscopic size. However, important questions on the HQV, such as its stability, have remained largely unexplored. We report in this paper the detection of distinct features in vortex crossing induced magnetoresistance (MR) oscillations in doubly connected, mesoscopic cylinders of single-crystal ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$, which include a dip and secondary peak in MR, in the presence of a sufficiently large in-plane magnetic field. We argue that these features are due to the formation of spin counterflow HQV in a spin-triplet superconductor, which provides additional evidence for the existence of HQV and insights into the physics of this highly unusual topological object.

Cascade of magnetic-field-driven quantum phase transitions in Ce3Pd20Si6

Magnetically hidden order is a hypernym for electronic ordering phenomena that are visible to macroscopic thermodynamic probes but whose microscopic symmetry cannot be revealed with conventional neutron or x-ray diffraction. In a handful of f-electron systems, the ordering of odd-rank multipoles leads to order parameters with a vanishing neutron cross-section. Among them, Ce$_3$Pd$_{20}$Si$_6$ is known for its unique phase diagram exhibiting two distinct multipolar-ordered ground states (phases II and II'), separated by a field-driven quantum phase transition associated with a putative change in the ordered quadrupolar moment from $O_2^0$ to $O_{xy}$. Using torque magnetometry at subkelvin temperatures, here we find another phase transition at higher fields above 12 T, which appears only for low-symmetry magnetic field directions $\mathbf{B} \parallel \langle11L\rangle$ with $1 < L \leq 2$. While the order parameter of this new phase II'' remains unknown, the discovery renders Ce$_3$Pd$_{20}$Si$_6$ a unique material with two field-driven phase transitions between distinct multipolar phases. They are both clearly manifested in the magnetic-field dependence of the field-induced (111) Bragg intensities measured with neutron scattering for $\mathbf{B} \parallel [112]$. We also find from inelastic neutron scattering that the number of nondegenerate collective excitations induced by the magnetic field correlates with the number of phases in the magnetic phase diagram for the same field direction. Furthermore, the magnetic excitation spectrum suggests that the new phase II'' may have a different propagation vector, revealed by the minimum in the dispersion that may represent the Goldstone mode of this hidden-order phase.