Computational Design of One‐Dimensional Ferromagnetic Semiconductors in Transition Metal Embedded Stannaspherene Nanowires

Chemically Controlled Reversible Magnetic Phase Transition in Two-Dimensional Organometallic Lattices

Developing an efficient method to reversibly control materials' spin order is urgently needed but challenging in spintronics. Though various physical field control methods have been advancing, the chemical control of spin is little exploited. Here, we propose a chemical means for such spin manipulation, i.e., utilizing the well-known lactim-lactam tautomerization to reversibly modulate the magnetic phase transition in two-dimensional (2D) organometallic lattices. The proposal is verified by theoretically designing several 2D organometallic frameworks with antiferromagnetic to ferrimagnetic spin order transformation modulated by lactim-lactam tautomerization on organic linkers. The transition originates from the change in spin states of organic linkers (from singlet to doublet) via tautomerization. Such a transition further switches materials' electronic structures from normal semiconductors with zero spin polarization to bipolar magnetic semiconductors with valence and conduction band edges 100% spin polarized in opposite spin channels. Moreover, the magnitude of magnetic anisotropy energy also enhances by 5- to 9-fold.

Two-Dimensional Multifunctional Metal-Organic Frameworks with Simultaneous Ferro-/Ferrimagnetism and Vertical Ferroelectricity

Exploring 2D multifunctional materials with intrinsic ferro-/ferrimagnetism and vertical ferroelectricity is a highly desirable but challenging task. Here, motivated by the recently synthesized organometallic frameworks K₃Fe₂[PcFeO₈], we propose to realize such materials in a series of 2D K₃M₂[PcMO₈] (M = Cr-Co) nanosheets. First-principles calculations suggest 2D K₃Cr₂[PcCrO₈] as a ferromagnetic half metal with a Curie temperature of 140 K, whereas others (M = Mn, Fe, and Co) are all ferrimagnetic semiconductors with the Curie temperatures between 66 and 150 K. Moreover, the structural distortion due to the out-of-plane K⁺ counterions leads to a significant vertical electric polarization. The estimated intensity of polarization for K₃Fe₂[PcFeO₈] is 143 pC/m, with the ferroelectric phase-transition barrier being 0.38 eV per formula. This work highlights the potential of 2D organometallic frameworks such as K₃M₂[PcMO₈] as a versatile platform for designing multifunctional materials with simultaneous ferro-/ferrimagnetism and vertical ferroelectricity.