Unconventional Spin State in a Rare Earth Iron Antimonide

An unusual magnetic behavior was discovered in the rare earth iron antimonide Pr3Fe3Sb7, which arises from a complex interplay of 3d and 4f magnetism. Crystal growth in a molten bismuth flux allowed the in-depth study of the bulk magnetic and electrical transport properties. A combined approach by extensive magnetization measurements, Mößbauer spectroscopy and neutron diffraction revealed the magnetic structure and the competing interactions of two different substructures.

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Unconventional Spin State in a Rare Earth Iron Antimonide

Mineral pump

To form an ore deposit, gold needs to be concentrated from a thousand up to a million times more than its average abundance in the Earth's crust (about 1 mg per ton of rock). In nature, only very few minerals, namely arsenian pyrite and arsenopyrite, are known to present such enrichment factors for gold. However, despite the enormous implications, the state of this ‘invisible' gold and the cause of its entrapment in these sulfides remains one of the greatest mysteries in the history of the study of ore deposits.

Reaction mechanism of the polyol process in the intermetallic Bi-Ni system

By trapping intermediates using a synthesis microwave, the formation mechanism of BiNi particles in the polyol process was revealed. A successive reduction with a subsequent diffusion process was determined. The reaction is dependent on various parameters, which have been investigated as well.

Dissolution of metal oxides in ionic liquid

The ionic liquid [Hbet][NTf2] is suitable for the dissolution of numerous metal oxides at low temperature. Starting from a resulting complex compound, first steps towards downstream chemistry were made.

Hydroflux Synthesis of oxo hydroxoferrate K(2–x)Fe4O(7–x)(OH)x

Reaction of iron(III) nitrate in a potassium hydroxide hydroflux leads to the oxo-hydroxoferrate(III) K(2−x)Fe4O(7–x)(OH)x. This compound shows an unusual vacancy ordering of the potassium positions and decomposes topotactically into β’’ or β-aluminate-type K(1+x’)Fe11O17.

Low-Temperature Ordering in the Cluster Compound (Bi8)Tl[AlCl4]3

Via reaction in the ionic liquid [BMIm]Cl·4AlCl3 we recently succeeded to synthesize (Bi8)Tl[AlCl4]3. In the cluster compound, that - at room temperature - may be regarded as a perovskite structure type with two complex ions, low temperature ordering of bismuth polycations could be observed.

From graphite and nitrogen to CCN3– in just one step

The elements carbon and nitrogen are generally unreactive. Reactive precursors like ammonia are thus employed for C–N bond-formation in organic synthesis. Surprisingly, the synthesis of CCN3– suceeded from the elements – a quasi organic molecular anion postulated decades ago. The anion is stabilized in the bulk host framework of the nitridometalate Ba5[TaN4][C2N].

bearbeitetes Foto eines Bismutkristalls und -würfels

On the trails of Fermi, Dirac and Weyl

A group of young scientists in the working group of Prof. Dr. Ruck is on a mission to find new topological non-trivial matter. In accordance with the work groups orientation on pnictogens, the research group focuses on compounds of bismuth.

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Unconventional Spin State in a Rare Earth Iron Antimonide

To gain a detailed understanding on the atomic scale of magnetic properties is crucial for the tailored design of magnetic materials. Compounds from rare earth and transition metal elements have attracted large research interest for a long time. They combine the two worlds of itinerant (3d) and localized (4f) electrons. Their interplay has been the origin of multiple interesting magnetic phenomena.

The ternary intermetallic Pr₃Fe₃Sb₇ has been described as a novel representative of such compounds. For the first time, crystal growth of mm-sized, needle-like crystals succeeded in a molten bismuth flux. They allowed the directional investigation of bulk magnetization and electrical transport properties. Cooling samples in an external magnetic field parallel to the c axis revealed a strong temperature and field dependency of the magnetization. A negative magnetization (opposite to the field direction) was observed that does not originate from superconductivity.

Combined magnetization measurements, Mößbauer spectroscopy and powder neutron diffraction gave detailed insights into this behavior. The crystal structure is composed of two spatially separated substructures of iron and praseodymium connected by an antimony framework. At low temperatures, a competing interaction between the two substructures emerges with antiparallel arrangement of the Fe and Pr moments. Magnetocrystalline anisotropy preserves the initial orientation of the moments, which results in the negative magnetization. At room temperature, only the moments of the iron substructure undergo long range ordering. As demonstrated by Mößbauer spectroscopy in field and zero-field conditions, two iron site coexist that feature different orientations of the moments.

The investigation of the complex magnetism in the ternary compound provides new insight into the possible magnetic interaction of intermetallic compounds. Since changes in temperature and external field result in a strong magnetic response, the material can potentially be used for magnetic switching.

The article can be found in Advanced Materials:

F. Pabst, S. Palazzese, F. Seewald, S. Yamamoto, D. Gorbunov, S. Chattopadhyay, T. Herrmannsdörfer, C. Ritter, K. Finzel, T. Doert, H. Klauss, J. Wosnitza, M. Ruck, Adv. Mater. 2022, 2207945.

Unconventional Spin State in a Rare Earth Iron Antimonide

Highlights at a glance

Unconven­tional Spin State in a Rare Earth Iron Antimonide

Mineral pump

Reaction mechanism of the polyol process in the intermetal­lic Bi-Ni system

Dissolution of metal oxides in ionic liquid

Hydroflux Synthesis of oxo hydroxofer­rate K(2–x)Fe4O(7–x)(OH)x

Low-Temperature Ordering in the Cluster Compound (Bi8)Tl[AlCl4]3

From graphite and nitrogen to CCN3– in just one step

On the trails of Fermi, Dirac and Weyl

Cover Gallery

Unconventional Spin State in a Rare Earth Iron Antimonide

Unconventional Spin State in a Rare Earth Iron Antimonide

Reaction mechanism of the polyol process in the intermetallic Bi-Ni system

Hydroflux Synthesis of oxo hydroxoferrate K(2–x)Fe4O(7–x)(OH)x