DCT

0:25-cv-01460

Mr Tech GmbH v. Seagate Technology LLC

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 0:25-cv-01460, D. Minn., 04/15/2025
  • Venue Allegations: Venue is alleged to be proper in the District of Minnesota because Defendant Seagate Technology LLC maintains regular and established places of business in Bloomington and Shakopee, Minnesota, and has committed acts of infringement in the District. The other defendants are foreign corporations, for which venue is proper in any district.
  • Core Dispute: Plaintiff alleges that Defendant’s perpendicular magnetic recording (PMR) hard disk drives (HDDs) infringe three patents related to multilayer exchange spring recording media technology.
  • Technical Context: The technology addresses the "superparamagnetic limit," a fundamental physical barrier in magnetic data storage, by using a novel multilayer media structure to enable higher storage densities while maintaining data stability and writeability.
  • Key Procedural History: The complaint heavily relies on a prior lawsuit (MR Techs. v. Western Digital, “MRT-I”) where a jury found the ’864 and ’997 patents were infringed by Seagate’s main competitor, resulting in a judgment of approximately $380 million. The complaint cites testimony from that trial, including from Seagate’s former CTO, to support its allegations. Plaintiff also alleges it provided notice of the parent patent applications to Seagate as early as 2012.

Case Timeline

Date Event
2006-05-01 Inventor used micromagnetics modeling software for the invention
2006-06-17 Earliest Priority Date for all Asserted Patents
2012-03-20 Plaintiff allegedly provided notice to Seagate of patent applications
2012-05-02 Seagate allegedly responded it was not interested in a license
2018-03-27 U.S. Patent No. 9,928,864 Issued
2021-10-05 U.S. Patent No. 11,138,997 Issued
2024-06-25 U.S. Patent No. 12,020,734 Issued
2024-07-26 Jury verdict in MRT-I against Western Digital
2024-08-14 Judgment entered in MRT-I against Western Digital
2025-04-15 Complaint Filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 9,928,864 - "Multilayer exchange spring recording media"

  • Patent Identification: U.S. Patent No. 9,928,864, "Multilayer exchange spring recording media", issued March 27, 2018. (Compl. ¶31).

The Invention Explained

  • Problem Addressed: The patent’s background describes the "superparamagnetic limit" in magnetic recording, where increasing data density requires smaller magnetic grains. These small grains can become thermally unstable, leading to data loss. Conventionally, increasing thermal stability (by increasing magnetic anisotropy) makes the media too "hard" to be written to by existing recording heads. (’864 Patent, col. 1:12-29).
  • The Patented Solution: The invention proposes a multilayer recording medium that decouples thermal stability from writeability. It consists of a thermally stable "hard magnetic storage layer" exchange-coupled to a "nucleation host." This host itself contains multiple ferromagnetic layers with progressively lower anisotropy farther from the hard layer. A write head can easily switch the "softest" layer of the host, and this magnetic reversal propagates through the graded layers—an "exchange spring" effect—to switch the underlying hard layer, thus enabling a reliable write operation without sacrificing stability. (’864 Patent, Abstract; col. 2:50-65).
  • Technical Importance: This "exchange spring" concept was a key innovation that enabled the HDD industry to continue increasing areal storage densities beyond what was thought possible with conventional media. (Compl. ¶19, 21-24).

Key Claims at a Glance

  • The complaint asserts at least independent claim 1. (Compl. ¶38, 42).
  • Essential elements of Claim 1:
    • A magnetic recording medium comprising an essentially non-magnetic substrate and an underlayer.
    • An exchange coupled magnetic multilayer structure formed on the underlayer.
    • The structure includes a "hard magnetic storage layer" with a first coercive field (Hs) greater than 0.5 Tesla.
    • The structure also includes a "nucleation host" with a second coercive field (Hn) that is lower than the first (Hn<Hs).
    • The nucleation host is formed on, and exchange coupled to, the hard magnetic storage layer.
    • The nucleation host "comprises ferromagnetic layers with increasing anisotropy constant K from layer to layer."

U.S. Patent No. 11,138,997 - "Multilayer exchange spring recording media"

  • Patent Identification: U.S. Patent No. 11,138,997, "Multilayer exchange spring recording media", issued October 5, 2021. (Compl. ¶63).

The Invention Explained

  • Problem Addressed: As a continuation of the same family, the '997 Patent addresses the same superparamagnetic limit and the associated writeability challenge in high-density magnetic media. (’997 Patent, col. 1:12-29).
  • The Patented Solution: The '997 patent claims a complete "magnetic recording system" (i.e., a hard drive) rather than just the recording medium. The system comprises a "writing head" and a "disk" that incorporates the same multilayer exchange spring medium described in the '864 Patent, featuring a hard storage layer coupled to a graded-anisotropy nucleation host. (’997 Patent, Claim 1).
  • Technical Importance: By claiming the entire system, the patent covers the end product (the HDD) that implements the core media invention. (Compl. ¶74).

Key Claims at a Glance

  • The complaint asserts at least independent claim 1. (Compl. ¶70, 74).
  • Essential elements of Claim 1:
    • A magnetic recording system comprising a "writing head" and a "disk."
    • The disk includes a magnetic recording medium with limitations that mirror those of claim 1 of the ’864 Patent, including the hard storage layer, the softer nucleation host, and the requirement for "ferromagnetic layers with increasing anisotropy constant K from layer to layer."

U.S. Patent No. 12,020,734 - "Multilayer exchange spring recording media"

  • Patent Identification: U.S. Patent No. 12,020,734, "Multilayer exchange spring recording media", issued June 25, 2024. (Compl. ¶81).
  • Technology Synopsis: This patent claims a magnetic recording system substantially similar to that of the ’997 Patent, addressing the superparamagnetic limit with an exchange spring medium. It introduces a more specific limitation, requiring that at least two of the ferromagnetic layers within the nucleation host are "exchange coupled with an exchange coupling layer." (’734 Patent, Claim 1; Compl. ¶85).
  • Asserted Claims: Independent claim 1 is asserted. (Compl. ¶89).
  • Accused Features: The accused HDDs are alleged to contain the exchange-coupled composite media, specifically including the use of thin "break layers" or "exchange coupling layers" (e.g., BL1, BL2, EBL) between the ferromagnetic layers of the nucleation host, as depicted in industry diagrams. (Compl. ¶85, p. 38).

III. The Accused Instrumentality

Product Identification

The accused instrumentalities are Seagate’s perpendicular magnetic recording (PMR) hard disk drives (HDDs), including both conventional (CMR) and shingled (SMR) versions, and the PMR media they contain. (Compl. ¶2). The complaint lists numerous product lines, including BarraCuda, IronWolf, SkyHawk, and Exos. (Compl. ¶32).

Functionality and Market Context

The accused HDDs are mass-market data storage devices used in products ranging from consumer laptops to enterprise and cloud data centers. (Compl. ¶11, 17). The complaint alleges that these drives achieve high areal densities (e.g., above 700 Gb/in²) by implementing the patented exchange-coupled composite ("ECC") media structure. (Compl. ¶29). It further positions Seagate as one of only three major HDD manufacturers, suggesting this technology is critical for market competition. (Compl. ¶35). The complaint includes photographs of the exterior of several accused HDD models. (Compl. ¶12, p. 4).

IV. Analysis of Infringement Allegations

'864 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A magnetic recording medium The accused products are PMR HDDs which contain a magnetic recording medium on at least one disk. An annotated image from a Seagate marketing video shows a 16TB Exos HDD with 9 disks. ¶42 col. 5:1-3
an essentially non-magnetic substrate The accused products are alleged to include a glass or AlMg substrate, which are non-magnetic. ¶43 col. 4:31-33
an underlayer formed on the non-magnetic substrate The accused products include a soft magnetic underlayer (SUL) formed on the substrate, as shown in a cross-sectional TEM image of perpendicular media. ¶44 col. 4:34-40
an exchange coupled magnetic multilayer structure...including a hard magnetic storage layer...and a nucleation host The accused products allegedly use an "exchange-coupled composite media" (ECC) structure, depicted as a stack with a hard magnetic storage layer and a softer, multi-layer nucleation host formed upon it. ¶45, 46 col. 5:40-65
[hard magnetic storage layer] having a first coercive field Hs>0.5 T On information and belief, the hard storage layer is made of a CoCrPt-type alloy with a coercive field of approximately 2.0 T, satisfying the >0.5 T requirement. ¶47, 49 col. 5:25-26
a nucleation host, having a second coercive field Hn...lower than the first coercive field, Hn<Hs The nucleation host allegedly has a coercive field (Hn) lower than the hard storage layer's coercive field (Hs). The complaint alleges Hn is < 1.8 T, while Hs is ~2.0 T. This functionality is described as the key to decoupling writeability from thermal stability. ¶51, 52, 54 col. 5:26-28
[nucleation host] comprises ferromagnetic layers with increasing anisotropy constant K from layer to layer The accused products allegedly employ a structure with "graded anisotropy," where multiple magnetic layers have anisotropy that increases toward the hard storage layer. This is illustrated with a diagram from a 2018 industry presentation. ¶56, 57; p. 9 col. 5:5-7

'997 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A magnetic recording system, comprising: a writing head; and a disk The accused HDDs are magnetic recording systems that contain both disks (platters) and read/write heads. An annotated image from a Seagate video shows the platters and "Read and write heads (Transducers are here)." ¶74 col. 14:21-23
[disk] including a magnetic recording medium, comprising... [all medium limitations] The complaint alleges that the magnetic recording medium on the disks of the accused HDDs meets all the medium limitations for the same reasons as alleged for the '864 Patent, incorporating those allegations by reference. ¶75 col. 14:24-42

Identified Points of Contention

  • Quantitative Proof: A primary point of contention may be the quantitative requirements of the claims, such as "Hs > 0.5 T" and "Hn < Hs". The complaint supports these allegations with calculations based on public industry materials and "information and belief" (Compl. ¶49, 54). The case may depend on whether discovery and expert analysis of the actual accused products confirm these specific physical properties.
  • Scope of "Increasing Anisotropy": The claim requires "ferromagnetic layers with increasing anisotropy constant K from layer to layer." The complaint cites a favorable construction from the MRT-I case, which allows for an "overall increase" even if there are intermediate plateaus or decreases in anisotropy between adjacent layers (Compl. ¶56). A key technical question will be whether the specific layering in Seagate’s media meets this "overall increase" standard, a determination that will require detailed materials analysis.

V. Key Claim Terms for Construction

  • The Term: "nucleation host ... comprises ferromagnetic layers with increasing anisotropy constant K from layer to layer"

  • Context and Importance: This term is the central technical concept of the invention, defining the structure that allegedly overcomes the writeability problem. The construction of "increasing ... from layer to layer" will determine whether a wide range of multilayer media designs fall within the scope of the claims.

  • Intrinsic Evidence for Interpretation:

    • Evidence for a Broader Interpretation: The specification describes optimizing the media by choosing a "functional form of K(z)" which can be linear, polynomial, or include "plateaus or steps" (’997 Patent, col. 8:40-49). This suggests the increase need not be strictly monotonic. The complaint reinforces this by citing the MRT-I court's construction, which permitted an "overall increase" toward the hard storage layer (Compl. ¶56).
    • Evidence for a Narrower Interpretation: A defendant could argue that the term "exchange spring" and the patent's own diagrams (e.g., '997 Patent, Fig. 1) imply a more specific, ordered structure of distinct layers with progressively increasing anisotropy. They might argue that structures with significant deviations from a progressive increase do not meet the claim language.

  • The Term: "coercive field" (as in "first coercive field Hs" and "second coercive field Hn")

  • Context and Importance: The infringement analysis depends on the quantitative comparison "Hn < Hs". The definition and method of determining the coercive field for the single "hard magnetic storage layer" versus the composite multi-layer "nucleation host" is therefore critical.

  • Intrinsic Evidence for Interpretation:

    • Evidence for a Broader Interpretation: The term is a standard one in physics. A party might argue for its plain and ordinary meaning, which is the intensity of the applied magnetic field required to reduce the magnetization of a material to zero after it has reached saturation.
    • Evidence for a Narrower Interpretation: The patent provides a specific methodology for calculating the effective properties of a multilayer structure, stating that the average anisotropy (Keff) and average magnetization (Meff) are determined by the thickness-weighted average of the constituent layers (’997 Patent, col. 6:55-61). The complaint adopts this approach (Compl. ¶53). Practitioners may focus on whether this specific calculation method disclosed in the specification should be read into the claim as the required method for determining the coercive field for the composite nucleation host.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges inducement by asserting that Defendants provide purpose-built HDDs to OEM customers like Dell, HPE, and IBM with the specific intent that these OEMs will incorporate the infringing drives into computer systems sold in the U.S. This intent is allegedly supported by marketing materials, datasheets, and engineering support for integration. (Compl. ¶37-40, 69-71).
  • Willful Infringement: Willfulness allegations are prominent and based on two main grounds. First, Plaintiff alleges providing direct notice to Seagate of the parent patent applications in March 2012. (Compl. ¶36, 68). Second, and more significantly, the complaint alleges that the July 2024 jury verdict and subsequent ~$380 million judgment against Seagate's main competitor, Western Digital, on the same patents and technology, provided undeniable knowledge of infringement. (Compl. ¶34, 41, 66).

VII. Analyst’s Conclusion: Key Questions for the Case

  • A key evidentiary question will be one of empirical validation: Can the Plaintiff, through discovery, produce direct physical evidence from Defendant's commercial products that validates the quantitative allegations made on information and belief—specifically, that the coercive fields and anisotropy gradients of the media layers meet the numerical and relational limitations required by the claims?
  • A central legal issue will be the impact of prior litigation: To what extent will the jury verdict and substantial judgment against Seagate's primary competitor on the same patents affect the analysis of willfulness and potential damages, especially in light of allegations that Seagate's own former CTO testified in the prior trial and that Seagate had pre-suit notice dating back to 2012?
  • The case may also present a question of infringement differentiation: Given that the '734 patent includes a more specific limitation requiring an "exchange coupling layer" between ferromagnetic layers, will the evidence show that all accused products meet this narrower requirement, or could this lead to a split infringement outcome where some products infringe the broader '864 and '997 patents but not the '734 patent?